The Project Gutenberg EBook of The World's Greatest Books - Volume 15 -
Science, by Various
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Title: The World's Greatest Books - Volume 15 - Science
Author: Various
Editor: John Alexander Hammerton
Release Date: May 17, 2008 [EBook #25509]
Language: English
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[Illustration: William Harvey]
THE WORLD'S
GREATEST
BOOKS
JOINT EDITORS
ARTHUR MEE
Editor and Founder of the Book of Knowledge
J.A. HAMMERTON
Editor of Harmsworth's Universal Encyclopaedia
VOL. XV
SCIENCE
WM. H. WISE & Co.
_Table of Contents_
PORTRAIT OF WILLIAM HARVEY _Frontispiece_
PAGE
BRAMWELL, JOHN MILNE
Hypnotism: Its History, Practice and Theory 1
BUFFON, COMTE DE
Natural History 12
CHAMBERS, ROBERT
Vestiges of Creation 22
CUVIER, GEORGES
The Surface of the Globe 33
DARWIN, CHARLES
The Origin of Species 43
DAVY, SIR HUMPHRY
Elements of Chemical Philosophy 64
FARADAY, MICHAEL
Experimental Researches in Electricity 75
The Chemical History of a Candle 85
FOREL, AUGUSTE
The Senses of Insects 95
GALILEO
Dialogues on the System of the World 105
GALTON, SIR FRANCIS
Essays in Eugenics 111
HAECKEL, ERNST
The Evolution of Man 123
HARVEY, WILLIAM
On the Motion of the Heart and Blood 136
HERSCHEL, SIR JOHN
Outlines of Astronomy 146
HUMBOLDT, ALEXANDER VON
Cosmos, a Sketch of the Universe 158
HUTTON, JAMES
The Theory of the Earth 170
LAMARCK
Zoological Philosophy 179
LAVATER, JOHANN
Physiogonomical Fragments 191
LIEBIG, JUSTUS VON
Animal Chemistry 203
LYELL, SIR CHARLES
The Principles of Geology 215
MAXWELL, JAMES CLERK
A Treatise on Electricity and Magnetism 227
METCHNIKOFF, ELIE
The Nature of Man 238
The Prolongation of Life 246
MILLER, HUGH
The Old Red Sandstone 255
NEWTON, SIR ISAAC
Principia 267
OWEN, SIR RICHARD
Anatomy of Vertebrates 280
VIRCHOW, RUDOLF
Cellular Pathology 292
* * * * *
A Complete Index of THE WORLD'S GREATEST BOOKS will be found at the end
of Volume XX.
_Acknowledgment_
Acknowledgment and thanks for the use of the following selections are
herewith tendered to the Open Court Publishing Company, La Salle, Ill.,
for "Senses of Insects," by Auguste Forel; to G.P. Putnam's Sons, New
York, for "Prolongation of Human Life" and "Nature of Man," by Elie
Metchnikoff; and to the De La More Press, London, for "Hypnotism, &c.,"
by Dr. Bramwell.
_Science_
JOHN MILNE BRAMWELL
Hypnotism: Its History, Practice and Theory
John Milne Bramwell was born in Perth, Scotland, May 11, 1852. The
son of a physician, he studied medicine in Edinburgh, and after
obtaining his degree of M.B., in 1873, he settled at Goole,
Yorkshire. Fired by the unfinished work of Braid, Bernheim and
Liébeault, he began, in 1889, a series of hypnotic researches,
which, together with a number of successful experiments he had
privately conducted, created considerable stir in the medical
world. Abandoning his general practice and settling in London in
1892, Dr. Bramwell became one of the foremost authorities in the
country on hypnotism as a curative agent. His Works include many
valuable treatises, the most important being "Hypnotism: its
History, Practice and Theory," published in 1903, and here
summarised for the WORLD'S GREATEST BOOKS by Dr. Bramwell himself.
_I.--Pioneers of Hypnotism_
Just as chemistry arose from alchemy, astronomy from astrology, so
hypnotism had its origin in mesmerism. Phenomena such as Mesmer
described had undoubtedly been observed from early times, but to his
work, which extended from 1756 to his death, in 1815, we owe the
scientific interest which, after much error and self-deception, finally
led to what we now term hypnotism.
John Elliotson (1791-1868), the foremost physician of his day, was the
leader of the mesmeric movement in England. In 1837, after seeing
Dupotet's work, he commenced to experiment at University College
Hospital, and continued, with remarkable success, until ordered to
desist by the council of the college. Elliotson felt the insult keenly,
indignantly resigned his appointments, and never afterwards entered the
hospital he had done so much to establish. Despite the persistent and
virulent attacks of the medical press, he continued his mesmeric
researches up to the time of his death, sacrificing friends, income and
reputation to his beliefs.
The fame of mesmerism spread to India, where, in 1845, James Esdaile
(1808-1859), a surgeon in the East India Company, determined to
investigate the subject. He was in charge of the Native Hospital at
Hooghly, and successfully mesmerised a convict before a painful
operation. Encouraged by this, he persevered, and, at the end of a year,
reported 120 painless operations to the government. Investigations were
instituted, and Esdaile was placed in charge of a hospital at Calcutta,
for the express purpose of mesmeric practice; he continued to occupy
similar posts until he left India in 1851. He recorded 261 painless
capital operations and many thousand minor ones, and reduced the
mortality for the removal of the enormous tumours of elephantiasis from
50 to 5 per cent.
According to Elliotson and Esdaile, the phenomena of mesmerism were
entirely physical in origin. They were supposed to be due to the action
of a vital curative fluid, or peculiar physical force, which, under
certain circumstances, could be transmitted from one human being to
another. This was usually termed the "od," or "odylic," force; various
inanimate objects, such as metals, crystals and magnets, were supposed
to possess it, and to be capable of inducing and terminating the
mesmeric state, or of exciting or arresting its phenomena.
The name of James Braid (1795-1860) is familiar to all students of
hypnotism. Braid was a Scottish surgeon, practising in Manchester, where
he had already gained a high reputation as a skilful surgeon, when, in
1841, he first began to investigate mesmerism. He successfully
demonstrated that the phenomena were entirely subjective. He published
"Neurypnology, or the Rationale of Nervous Sleep," in 1843, and invented
the terminology we now use. This was followed by other more or less
important works, of which I have been able to trace forty-one, but all
have been long out of print.
During the eighteen years Braid devoted to the study of hypnotism, his
views underwent many changes and modifications. In his first theory, he
explained hypnosis from a physical standpoint; in the second, he
considered it to be a condition of involuntary monoideism and
concentration, while his third theory differed from both. He recognised
that reason and volition were unimpaired, and that the attention could
be simultaneously directed to more points than one. The condition,
therefore, was not one of monoideism. He realised more and more that the
state was a conscious one, and that the losses of memory which followed
on waking could always be restored in subsequent hypnoses. Finally, he
described as "double consciousness" the condition he had first termed
"hypnotic," then "monoideistic."
Braid maintained an active interest in hypnotism up to his death, and,
indeed, three days before it, sent his last MS. to Dr. Azam, of
Bordeaux, "as a mark of esteem and regard." Sympathetic notices appeared
in the press after his death, all of which bore warm testimony to his
professional character. Although hypnotic work practically ceased in
England at Braid's death, the torch he had lighted passed into France.
In 1860, Dr. A.A. Liébeault (1823-1900) began to study hypnotism
seriously, and four years later gave up general practice, settled in
Nancy, and practised hypnotism gratuitously among the poor. For twenty
years his labours were unrecognised, then Bernheim (one of whose
patients Liébeault had cured) came to see him, and soon became a zealous
pupil. The fame of the Nancy school spread, Liébeault's name became
known throughout the world, and doctors flocked to study the new
therapeutic method.
While Liébeault's work may justly be regarded as a continuation of
Braid's, there exists little difference between the theories of Charcot
and the Salpêtrière school and those of the later mesmerists.
_II.--Theory of Hypnotism_
The following is a summary of Braid's latest theories: (1) Hypnosis
could not be induced by physical means alone. (2) Hypnotic and so-called
mesmeric phenomena were subjective in origin, and both were excited by
direct or by indirect suggestion. (3) Hypnosis was characterised by
physical as well as by psychical changes. (4) The simultaneous
appearance of several phenomena was recognised, and much importance was
attached to the intelligent action of a secondary consciousness. (5)
Volition was unimpaired, moral sense increased, and suggested crime
impossible. (6) _Rapport_ was a purely artificial condition created by
suggestion. (7) The importance of direct verbal suggestion was fully
recognised, as also the mental influence of physical methods. Suggestion
was regarded as the device used for exciting the phenomena, and not
considered as sufficient to explain them. (8) Important differences
existed between hypnosis and normal sleep. (9) Hypnotic phenomena might
be induced without the subject having passed through any condition
resembling sleep. (10) The mentally healthy were the easiest, the
hysterical the most difficult, to influence.
In England, during Braid's lifetime, his earlier views were largely
adopted by certain well-known men of science, particularly by Professors
W.B. Carpenter and J. Hughes Bennett, but they appear to have known
little or nothing of his latest theories. Bennett's description of the
probable mental and physical conditions involved in the state Braid
described as "monoideism" is specially worthy of note. Not only is it
interesting in itself, but it serves also as a standard of comparison
with which to measure the theories of later observers, who have
attempted to explain hypnosis by cerebral inhibition, psychical
automatism, or both these conditions combined.
(a) _Physiological._--According to Bennett, hypnosis was characterised
by alterations in the functional activity of the nerve tubes of the
white matter of the cerebral lobes. He suggested that a certain
proportion of these became paralysed through continued monotonous
stimulation; while the action of others was consequently exalted. As
these tubes connected the cerebral ganglion-cells, suspension of their
functions was assumed to bring with it interruption of the connection
between the ganglion-cells.
(b) _Psychical._--From the psychical side, he explained the phenomena of
hypnosis by the action of predominant and unchecked ideas. These were
able to obtain prominence from the fact that other ideas, which, under
ordinary circumstances, would have controlled their development, did not
arise, because the portion of the brain with which the latter were
associated had its action temporarily suspended--_i.e._, the connection
between the ganglion-cells was broken, owing to the interrupted
connection between the "fibres of association." Thus, he said, the
remembrance of a sensation could always be called up by the brain; but,
under ordinary circumstances, from the exercise of judgment, comparison,
and other mental faculties, we knew it was only a remembrance. When
these faculties were exhausted, the suggested idea predominated, and the
individual believed in its reality. Thus, he attributed to the faculties
of the mind a certain power of correcting the fallacies which each of
them was likely to fall into; just as the illusions of one sense were
capable of being detected by the healthy use of the other senses. There
were mental and sensorial illusions, the former caused by predominant
ideas and corrected by proper reasoning, the latter caused by perversion
of one sense and corrected by the right application of the others.
In hypnosis, according to this theory, a suggested idea obtained
prominence and caused mental and sensorial illusions, because the check
action--the inhibitory power--of certain higher centres had been
temporarily suspended. These theories were first published by Professor
Bennett in 1851.
_III.--Hypnotic Induction_
The methods by which hypnosis is induced have been classed as follows:
(1) physical; (2) psychical; (3) those of the magnetisers. The modern
operator, whatever his theories may be, borrows his technique from
Mesmer and Liébeault with equal impartiality, and thus renders
classification impossible. The members of the Nancy school, while
asserting that everything is due to suggestion, do not hesitate to use
physical means, and, if these fail, Bernheim has recourse to narcotics.
The following is now my usual method: I rarely begin treatment the first
time I see a patient, but confine myself to making his acquaintance,
hearing his account of his case, and ascertaining his mental attitude
with regard to suggestion. I usually find, from the failure of other
methods of treatment, that he is more or less sceptical as to the chance
of being benefited. I endeavour to remove all erroneous ideas, and
refuse to begin treatment until the patient is satisfied of the safety
and desirability of the experiment. I never say I am certain of being
able to influence him, but explain how much depends on his mental
attitude and power of carrying out my directions. I further explain to
the patient that next time he comes to see me I shall ask him to close
his eyes, to concentrate his attention on some drowsy mental picture,
and try to turn it away from me. I then make suggestions of two kinds:
the first refer to the condition I wish to induce while he is actually
in the armchair, thus, "Each time you see me, you will find it easier to
concentrate your attention on something restful. I do not wish you to go
to sleep, but if you can get into the drowsy condition preceding natural
sleep, my suggestions are more likely to be responded to." I explain
that I do not expect this to happen at once, although it does occur in
rare instances, but it is the repetition of the suggestions made in this
particular way which brings about the result. Thus, from the very first
treatment, the patient is subjected to two distinct processes, the
object of one being to induce the drowsy, suggestible condition, that of
the other to cure or relieve disease.
I wish particularly to mention that although I speak of hypnotism and
hypnosis--and it is almost impossible to avoid doing so--I rarely
attempt to induce so-called hypnosis, and find that patients respond to
treatment as readily, and much more quickly, now that I start curative
suggestions and treatment simultaneously, than they did in the days when
I waited until hypnosis was induced before making curative suggestions.
I have obtained good results in treating all forms of hysteria,
including _grande hysterie_, neurasthenia, certain forms of insanity,
dipsomania and chronic alcoholism, morphinomania and other drug habits,
vicious and degenerate children, obsessions, stammering, chorea,
seasickness, and all other forms of functional nervous disturbances.
It is impossible to discuss the different theories in detail here, but I
will briefly summarise the more important points, (1) Hypnotism, as a
science, rests on the recognition of the subjective nature of its
phenomena. (2) The theories of Charcot and the Salpêtrière school are
practically a reproduction of mesmeric error. (3) Liébeault and his
followers combated the views of the Salpêtrière school and successfully
substituted their own, of which the following are the important points:
(_a_) Hypnosis is a physiological condition, which can be induced in the
healthy. (_b_) In everyone there is a tendency to respond to suggestion,
but in hypnosis this condition is artificially increased. (_c_)
Suggestion explains all. Despite the fact that the members of the Nancy
school regard the condition as purely physiological and simply an
exaggeration of the normal, they consider it, in its profound stages at
all events, a form of automatism.
These and other views of the Nancy school have been questioned by
several observers. As Myers justly pointed out, although suggestion is
the artifice used to excite the phenomena, it does not create the
condition on which they depend. The peculiar state which enables the
phenomena to be evoked is the essential thing, not the signal which
precedes their appearance.
Within recent times another theory has arisen, which, instead of
explaining hypnotism by the arrested action of some of the brain centres
which subserve normal life, attempts to do so by the arousing of certain
powers over which we normally have little or no control. This theory
appears under different names, "Double Consciousness," "Das Doppel-Ich,"
etc., and the principle on which it depends is largely admitted by
science. William James, for example, says: "In certain persons, at
least, the total possible consciousness may be split into parts which
co-exist, but mutually ignore each other."
The clearest statement of this view was given by the late Frederic
Myers; he suggested that the stream of consciousness in which we
habitually lived was not our only one. Possibly our habitual
consciousness might be a mere selection from a multitude of thoughts
and sensations--some, at least, equally conscious with those we
empirically knew. No primacy was granted by this theory to the ordinary
waking self, except that among potential selves it appeared the fittest
to meet the needs of common life. As a rule, the waking life was
remembered in hypnosis, and the hypnotic life forgotten in the waking
state; this destroyed any claim of the primary memory to be the sole
memory. The self below the threshold of ordinary consciousness Myers
termed the "subliminal consciousness," and the empirical self of common
experience the "supraliminal." He held that to the subliminal
consciousness and memory a far wider range, both of physiological and
psychical activity, was open than to the supraliminal. The latter was
inevitably limited by the need of concentration upon recollections
useful in the struggle for existence; while the former included much
that was too rudimentary to be retained in the supraliminal memory of an
organism so advanced as that of man. The recollection of processes now
performed automatically and needing no supervision, passed out of the
supraliminal memory, but might be retained by the subliminal. The
subliminal, or hypnotic, self could exercise over the vaso-motor and
circulatory systems a degree of control unparalleled in waking life.
Thus, according to the Nancy school, the deeply hypnotised subject
responds automatically to suggestion before his intellectual centres
have had time to bring their inhibitory action into play; but, on the
other hand, in the subliminal consciousness theory, volition and
consciousness are recognised to be unimpaired in hypnosis.
_IV.--Curative Value of Hypnotism_
The intelligent action of the secondary self may be illustrated by the
execution of certain post-hypnotic acts. Thus, one of my patients who,
at a later period, consented to become the subject of experiment,
developed an enormously increased power of time appreciation. If told,
during hypnosis, for example, that she was to perform some specific act
in the waking state at the expiration of a complicated number of
minutes, as, for example, 40,825, she generally carried out the
suggestion with absolute accuracy. In this and similar experiments,
three points were noted. (1) The arithmetical problems were far beyond
her normal powers; (2) she normally possessed no special faculty for
appreciating time; (3) her waking consciousness retained no recollection
of the experimental suggestions or of anything else that had occurred
during hypnosis.
It is difficult to estimate the exact value of suggestion in connection
with other forms of treatment. There are one or two broad facts which
ought to be kept in mind.
1. Suggestion is a branch of medicine, which is sometimes combined by
those who practise it with other forms of treatment. Thus it is often
difficult to say what proportion of the curative results is due to
hypnotism and what to other remedies.
2. On the other hand, many cases of functional nervous disorder have
recovered under suggestive treatment after the continued failure of
other methods. Further, the diseases which are frequently cured are
often those in which drugs are of little or no avail. For example, what
medicine would one prescribe for a man in good physical health who had
suddenly become the prey of an obsession? Such patients are rarely
insane; they recognise that the idea which torments them is morbid; but
yet they are powerless to get rid of it.
3. In estimating the results of suggestive treatment, it must not be
forgotten that the majority of cases are extremely unfavourable ones. As
the value of suggestion and its freedom from danger become more fully
recognised, it will doubtless be employed in earlier stages of disease.
4. It should be clearly understood that the object of all suggestive
treatment ought to be the development of the patient's will power and
control of his own organism. Much disease would be prevented if we could
develop and control moral states.
BUFFON
Natural History
Georges Louis Leclerc, created in 1773 Comte de Buffon, was born at
Montbard, in France, on September 7, 1707. Evincing a marked bent
for science he became, in 1739, director of the Jardin du Roi and
the King's Museum in Paris. He had long contemplated the
preparation of a complete History of Nature, and now proceeded to
carry out the work. The first three volumes of the "Histoire
Naturelle, Générale et Particulière" appeared in 1749, and other
volumes followed at frequent intervals until his death at Paris on
April 16, 1788. Buffon's immense enterprise was greeted with
abounding praise by most of his contemporaries. On July 1, 1752, he
was elected to the French Academy in succession to Languet de
Gergy, Archbishop of Sens, and, at his reception on August 25 in
the following year, pronounced the oration in which occurred the
memorable aphorism, "Le style est l'homme même" (The style is the
very man). Buffon also anticipated Thomas Carlyle's definition of
genius ("which means the transcendent capacity of taking trouble,
first of all") by his famous axiom, "Le génie n'est autre chose
qu'une grande aptitude à la patience."
_Scope of the Work_
Buffon planned his "Natural History" on an encyclopaedic scale. His
point of view was unique. Natural history in its widest sense, he tells
us, embraces every object in the visible universe. The obvious divisions
of the subject, therefore, are, first, the earth, the air, and the
water; then the animals--quadrupeds, birds, fishes, and so
on--inhabiting each of these "elements," to use the phrase of his day.
Now, Buffon argued, if man were required to give some account of the
animals by which he was surrounded, of course he would begin with those
with which he was most familiar, as the horse, the dog, the cow. From
these he would proceed to the creatures with which he was less familiar,
and finally deal--through the medium of travellers' tales and other
sources of information--with the denizens of field, forest and flood in
foreign lands. In similar fashion he would consider the plants,
minerals, and other products of Nature, in addition to recounting the
marvels revealed to him by astronomy.
Whatever its defects on the scientific side, Buffon's plan was
simplicity itself, and was adopted largely, if not entirely, in
consequence of his contempt--real or affected--for the systematic method
of the illustrious Linnæus. Having charted his course, the rest was
plain sailing. He starts with the physical globe, discussing the
formation of the planets, the features of the earth--mountains, rivers,
seas, lakes, tides, currents, winds, volcanoes, earthquakes, islands,
and so forth--and the effects of the encroachment and retreat of the
ocean.
Animate nature next concerns him. After comparing animals, plants and
minerals, he proceeds to study man literally from the cradle to the
grave, garnishing the narrative with those incursions into the domains
of psychology, physiology and hygiene, which, his detractors insinuated,
rendered his work specially attractive and popular.
_I.--The Four-Footed Animals_
Such questions occupied the first three volumes, and the ground was now
cleared for the celebrated treatise on Quadrupeds, which filled no fewer
than twelve volumes, published at various dates from 1753 (vol. iv.) to
1767 (vol. xv., containing the New World monkeys, indexes, and the
like). Buffon's _modus operandi_ saved him from capital blunders. Though
inordinately vain--"I know but five great geniuses," he once said;
"Newton, Bacon, Leibniz, Montesquieu, and myself"--he was quite
conscious of his own limitations, and had the common-sense to entrust to
Daubenton the description of the anatomy and other technical matters as
to which his own knowledge was comparatively defective. He reserved to
himself what may be called the "literary" aspect of his theme, recording
the place of each animal in history, and relating its habits with such
gusto as his ornate and grandiose style permitted.
After a preliminary dissertation on the nature of animals, Buffon
plunges into an account of those that have been domesticated or tamed.
Preference of place is given to the horse, and his method of treatment
is curiously anticipatory of modern lines. Beginning with some notice of
the horse in history, he goes on to describe its appearance and habits
and the varieties of the genus, ending (by the hand of Daubenton) with
an account of its structure and physiology. As evidence of the pains he
took to collect authority for his statements, it is of interest to
mention that he illustrates the running powers of the English horse by
citing the instance of Thornhill, the postmaster of Stilton, who, in
1745, wagered he would ride the distance from Stilton to London thrice
in fifteen consecutive hours. Setting out from Stilton, and using eight
different horses, he accomplished his task in 3 hours 51 minutes. In the
return journey he used six horses, and took 3 hours 52 minutes. For the
third race he confined his choice of horses to those he had already
ridden, and, selecting seven, achieved the distance in 3 hours 49
minutes. He performed the undertaking in 11 hours and 32 minutes. "I
doubt," comments Buffon, "whether in the Olympic Games there was ever
witnessed such rapid racing as that displayed by Mr. Thornhill."
Justice having been done to it, the horse gives place to the ass, ox,
sheep, goat, pig, dog, and cat, with which he closes the account of the
domesticated animals, to which three volumes are allotted. It is
noteworthy that Buffon frequently, if not always, gives the synonyms of
the animals' names in other languages, and usually supports his textual
statements by footnote references to his authorities.
When he comes to the Carnivores--"les animaux nuisibles"--the defects of
Buffon's higgledy-piggledy plan are almost ludicrously evident, for
flesh-eaters, fruit-eaters, insect-eaters, and gnawers rub shoulders
with colossal indifference. Doubtless, however, this is to us all the
more conspicuous, because use and wont have made readers of the present
day acquainted with the advantages of classification, which it is but
fair to recognise has been elaborated and perfected since Buffon's time.
As his gigantic task progressed, Buffon's difficulties increased. At the
beginning of vol. xii. (1764) he intimates that, with a view to break
the monotony of a narrative in which uniformity is an unavoidable
feature, he will in future, from time to time, interrupt the general
description by discourses on Nature and its effects on a grand scale.
This will, he naively adds, enable him to resume "with renewed courage"
his account of details the investigation of which demands "the calmest
patience, and affords no scope for genius."
_II.--The Birds_
Scarcely had he finished the twelve volumes of Quadrupeds when Buffon
turned to the Birds. If this section were less exacting, yet it made
enormous claims upon his attention, and nine volumes were occupied
before the history of the class was concluded. Publication of "Des
Oiseaux" was begun in 1770, and continued intermittently until 1783. But
troubles dogged the great naturalist. The relations between him and
Daubenton had grown acute, and the latter, unwilling any longer to put
up with Buffon's love of vainglory, withdrew from the enterprise to
which his co-operation had imparted so much value. Serious illness,
also, and the death of Buffon's wife, caused a long suspension of his
labours, which were, however, lightened by the assistance of Guéneau de
Montbéliard.
One stroke of luck he had, which no one will begrudge the weary Titan.
James Bruce, of Kinnaird, on his return from Abyssinia in 1773, spent
some time with Buffon at his château in Montbard, and placed at his
disposal several of the remarkable discoveries he had made during his
travels. Buffon was not slow to appreciate this godsend. Not only did
he, quite properly, make the most of Bruce's disinterested help, but he
also expressed the confident hope that the British Government would
command the publication of Bruce's "precious" work. He went on to pay a
compliment to the English, and so commit them to this enterprise. "That
respectable nation," he asserts, "which excels all others in discovery,
can but add to its glory in promptly communicating to the world the
results of the excellent travellers' researches."
Still unfettered by any scheme of classification, either scientific or
logical, Buffon begins his account of the birds with the eagles and
owls. To indicate his course throughout the vast class, it will suffice
to name a few of the principal birds in the order in which he takes them
after the birds of prey. These, then, are the ostrich, bustard, game
birds, pigeons, crows, singing birds, humming birds, parrots, cuckoos,
swallows, woodpeckers, toucans, kingfishers, storks, cranes, secretary
bird, herons, ibis, curlews, plovers, rails, diving birds, pelicans,
cormorants, geese, gulls, and penguins. With the volume dealing with the
picarian birds (woodpeckers) Buffon announces the withdrawal of Guéneau
de Montbéliard, and his obligations for advice and help to the Abbé
Bexon (1748-1784), Canon of Sainte Chapelle in Paris.
_III.--Supplement and Sequel_
At the same time that the Birds volumes were passing through the press,
Buffon also issued periodically seven volumes of a supplement
(1774-1789), the last appearing posthumously under the editorship of
Count Lacépède. This consisted of an olla podrida of all sorts of
papers, such as would have won the heart of Charles Godfrey Leland. The
nature of the hotchpotch will be understood from a recital of some of
its contents, in their chronological order. It opened with an
introduction to the history of minerals, partly theoretical (concerning
light, heat, fire, air, water, earth, and the law of attraction), and
partly experimental (body heat, heat in minerals, the nature of
platinum, the ductility of iron). Then were discussed incandescence,
fusion, ships' guns, the strength and resistance of wood, the
preservation of forests and reafforestation, the cooling of the earth,
the temperature of planets, additional observations on quadrupeds
already described, accounts of animals not noticed before, such as the
tapir, quagga, gnu, nylghau, many antelopes, the vicuña, Cape ant-eater,
star-nosed mole, sea-lion, and others; the probabilities of life (a
subject on which the author plumed himself), and his essay on the Epochs
of Nature.
Nor did these concurrent series of books exhaust his boundless energy
and ingenuity, for in the five years preceding his death (1783-1788), he
produced his "Natural History of Minerals" in five volumes, the last of
which was mainly occupied with electricity, magnetism, and the
loadstone. It is true that the researches of modern chemists have
wrought havoc with Buffon's work in this field; but this was his
misfortune rather than his fault, and leaves untouched the quantity of
his output.
Buffon invoked the aid of the artist almost from the first, and his
"Natural History" is illustrated by hundreds of full-page copper-plate
engravings, and embellished with numerous elegant headpiece designs. The
figures of the animals are mostly admirable examples of portraiture,
though the classical backgrounds lend a touch of the grotesque to many
of the compositions. Illustrations of anatomy, physiology, and other
features of a technical character are to be numbered by the score, and
are, of course, indispensable in such a work. The _editio princeps_ is
cherished by collectors because of the 1,008 coloured plates ("Planches
Enluminées") in folio, the text itself being in quarto, by the younger
Daubenton, whose work was spiritedly engraved by Martinet. Apparently
anxious to illustrate one section exhaustively rather than several
sections in a fragmentary manner, the artist devoted himself chiefly to
the birds, which monopolise probably nine-tenths of the plates, and to
which he may also have been attracted by their gorgeous plumages.
As soon as the labourer's task was over, his scientific friends thought
the best monument which they could raise to his memory was to complete
his "Natural History." This duty was discharged by two men, who, both
well qualified, worked, however, on independent lines. Count Lacépède,
adhering to the format of the original, added two volumes on the
Reptiles (1788-1789), five on the Fishes (1798-1803), and one on the
Cetaceans (1804). Sonnini de Manoncourt (1751-1812), feeling that this
edition, though extremely handsome, was cumbersome, undertook an
entirely new edition in octavo. This was begun in 1797, and finished in
1808. It occupied 127 volumes, and, Lacépède's treatises not being
available, Sonnini himself dealt with the Fishes (thirteen volumes) and
Whales (one volume), P.A. Latreille with the Crustaceans and Insects
(fourteen volumes), Denys-Montfort with the Molluscs (six volumes), F.M.
Dandin with the Reptiles (eight volumes), and C.F. Brisseau-Mirbel and
N. Jolyclerc with the Plants (eighteen volumes). Sonnini's edition
constituted the cope-stone of Buffon's work, and remained the best
edition, until the whole structure was thrown down by the views of later
naturalists, who revolutionised zoology.
_IV.--Place and Doctrine_
Buffon may justly be acclaimed as the first populariser of natural
history. He was, however, unscientific in his opposition to systems,
which, in point of fact, essentially elucidated the important doctrine
that a continuous succession of forms runs throughout the animal
kingdom. His recognition of this principle was, indeed, one of his
greatest services to the science.
Another of his wise generalisations was that Nature proceeds by unknown
gradations, and consequently cannot adapt herself to formal analysis,
since she passes from one species to another, and often from one genus
to another, by shades of difference so delicate as to be wholly
imperceptible.
In Buffon's eyes Nature is an infinitely diversified whole which it is
impossible to break up and classify. "The animal combines all the powers
of Nature; the forces animating it are peculiarly its own; it wishes,
does, resolves, works, and communicates by its senses with the most
distant objects. One's self is a centre where everything agrees, a point
where all the universe is reflected, a world in miniature." In natural
history, accordingly, each animal or plant ought to have its own
biography and description.
Life, Buffon also held, abides in organic molecules. "Living beings are
made up of these molecules, which exist in countless numbers, which may
be separated but cannot be destroyed, which pierce into brute matter,
and, working there, develop, it may be animals, it may be plants,
according to the nature of the matter in which they are lodged. These
indestructible molecules circulate throughout the universe, pass from
one being to another, minister to the continuance of life, provide for
nutrition and the growth of the individual, and determine the
reproduction of the species."
Buffon further taught that the quantity and quality of life pass from
lower to higher stages--in Tennysonian phrase, men "rise on
stepping-stones of their dead selves to higher things"--and showed the
unity and structure of all beings, of whom man is the most perfect type.
It has been claimed that Buffon in a measure anticipated Lamarck and
Darwin. He had already foreseen the mutability of species, but had not
succeeded in proving it for varieties and races. If he asserted that the
species of dog, jackal, wolf and fox were derived from a single one of
these species, that the horse came from the zebra, and so on, this was
far from being tantamount to a demonstration of the doctrine. In fact,
he put forward the mutability of species rather as probable theory than
as established truth, deeming it the corollary of his views on the
succession and connection of beings in a continuous series.
Some case may be made out for regarding Buffon as the founder of
zoogeography; at all events he was the earliest to determine the natural
habitat of each species. He believed that species changed with climate,
but that no kind was found throughout all the globe. Man alone has the
privilege of being everywhere and always the same, because the human
race is one. The white man (European or Caucasian), the black man
(Ethiopian), the yellow man (Mongol), and the red man (American) are
only varieties of the human species. As the Scots express it with wonted
pith, "We're a' Jock Tamson's bairns."
As to his geological works, Buffon expounded two theories of the
formation of the globe. In his "Théorie de la Terre" he supported the
Neptunists, who attributed the phenomena of the earth to the action of
water. In his "Epoques de la Nature" he amplified the doctrines of
Leibniz, and laid down the following propositions: (1) The earth is
elevated at the equator and depressed at the poles in accordance with
the laws of gravitation and centrifugal force; (2) it possesses an
internal heat, apart from that received from the sun; (3) its own heat
is insufficient to maintain life; (4) the substances of which the earth
is composed are of the nature of glass, or can be converted into glass
as the result of heat and fusion--that is, are verifiable; (5)
everywhere on the surface, including mountains, exist enormous
quantities of shells and other maritime remains.
To the theses just enumerated Buffon added what he called the
"monuments," or what Hugh Miller, a century later, more aptly described
as the Testimony of the Rocks. From a consideration of all these things,
Buffon at length arrived at his succession of the Epochs, or Seven Ages
of Nature, namely: (1) the Age of fluidity, or incandescence, when the
earth and planets assumed their shape; (2) the Age of cooling, or
consolidation, when the rocky interior of the earth and the great
vitrescible masses at its surface were formed; (3) the Age when the
waters covered the face of the earth; (4) the Age when the waters
retreated and volcanoes became active; (5) the Age when the elephant,
hippopotamus, rhinoceros, and other giants roamed through the northern
hemisphere; (6) the Age of the division of the land into the vast areas
now styled the Old and the New Worlds; and (7) the Age when Man
appeared.
ROBERT CHAMBERS
Vestiges of Creation
Robert Chambers was born in Peebles, Scotland, July 10, 1802, and
died at St. Andrews on March 17, 1871. He was partner with his
brother in the publishing firm of W. & R. Chambers, was editor of
"Chambers's Journal," and was author of several works when he
published anonymously, in October 1844, the work by which his name
will always be remembered, "Vestiges of the Natural History of
Creation." His previous works, some thirty in number, did not deal
with science, and his labour in preparing his masterpiece was
commensurate with the courage which such an undertaking involved.
When the book was published, such interest and curiosity as to its
authorship were aroused that we have to go back to the publication
of "Waverley" for a parallel. Little else was talked about in
scientific circles. The work was violently attacked by many hostile
critics, F.W. Newman, author of an early review, being a
conspicuous exception. In the historical introduction to the
"Origin of Species," Darwin speaks of the "brilliant and powerful
style" of the "Vestiges," and says that "it did excellent service
in this country in calling attention to the subject, in removing
prejudice, and in thus preparing the ground for the reception of
analogous views." Darwin's idea of selection as the key to the
history of species does not occur in the "Vestiges," which belongs
to the Lamarckian school of unexamined belief in the hereditary
transmission of the effects of use and disuse.
_I.--The Reign of Universal Law_
The stars are suns, and we can trace amongst them the working of the
laws which govern our sun and his family. In these universal laws we
must perceive intelligence; something of which the laws are but as the
expressions of the will and power. The laws of Nature cannot be regarded
as primary or independent causes of the phenomena of the physical world.
We come, in short, to a Being beyond Nature--its author, its God;
infinite, inconceivable, it may be, and yet one whom these very laws
present to us with attributes showing that our nature is in some way a
faint and far-cast shadow of His, while all the gentlest and the most
beautiful of our emotions lead us to believe that we are as children in
His care and as vessels in His hand. Let it then be understood--and this
for the reader's special attention--that when natural law is spoken of
here, reference is made only to the mode in which the Divine Power is
exercised. It is but another phrase for the action of the ever-present
and sustaining God.
Viewing Nature in this light, the pursuit of science is but the seeking
of a deeper acquaintance with the Infinite. The endeavour to explain any
events in her history, however grand or mysterious these may be, is only
to sit like a child at a mother's knee, and fondly ask of the things
which passed before we were born; and in modesty and reverence we may
even inquire if there be any trace of the origin of that marvellous
arrangement of the universe which is presented to our notice. In this
inquiry we first perceive the universe to consist of a boundless
multitude of bodies with vast empty spaces between. We know of certain
motions among these bodies; of other and grander translations we are
beginning to get some knowledge. Besides this idea of locality and
movement, we have the equally certain one of a former soft and more
diffused state of the materials of these bodies; also a tolerably clear
one as to gravitation having been the determining cause of both locality
and movement. From these ideas the general one naturally suggested to us
is--a former stage in the frame of material things, perhaps only a point
in progress from some other, or a return from one like the
present--universal space occupied with gasiform matter. This, however,
was of irregular constitution, so that gravitation caused it to break up
and gather into patches, producing at once the relative localities of
astral and solar systems, and the movements which they have since
observed, in themselves and with regard to each other--from the daily
spinning of single bodies on their own axes, to the mazy dances of vast
families of orbs, which come to periods only in millions of years.
How grand, yet how simple the whole of this process--for a God only to
conceive and do, and yet for man, after all, to trace out and ponder
upon. Truly must we be in some way immediate to the august Father, who
can think all this, and so come into His presence and council, albeit
only to fall prostrate and mutely adore.
Not only are the orbs of space inextricably connected in the manner
which has been described, but the constitution of the whole is uniform,
for all consist of the same chemical elements. And now, in our version
of the romance of Nature, we descend from the consideration of
orb-filled space and the character of the universal elements, to trace
the history of our own globe. And we find that this falls significantly
into connection with the primary order of things suggested by Laplace's
theory of the origin of the solar system in a vast nebula or fire-mist,
which for ages past has been condensing under the influence of
gravitation and the radiation of its heat.
_II.--History of the Earth's Crust_
When we study the earth's crust we find that it consists of layers or
strata, laid down in succession, the earlier under the influence of
heat, the later under the influence of water. These strata in their
order might be described as a record of the state of life upon our
planet from an early to a comparatively recent period. It is truly such
a record, but not one perfectly complete.
Nevertheless, we find a noteworthy and significant sequence. We learn
that there was dry land long before the occurrence of the first fossils
of land plants and animals. In different geographical formations we
find various species, though sometimes the same species is found in
different formations, having survived the great earth changes which the
record of the rocks indicates. There is an unbroken succession of animal
life from the beginning to the present epoch. Low down, where the
records of life begin, we find an era of backboneless animals only, and
the animal forms there found, though various, are all humble in their
respective lines of gradation.
The early fishes were low, both with respect to their class as fishes,
and the order to which they belong--that of the cartilaginous or gristly
fishes. In all the orders of ancient animals there is an ascending
gradation of character from first to last. Further, there is a
succession from low to high types in fossil plants, from the earliest
strata in which they are found to the highest. Several of the most
important living species have left no record of themselves in any
formation beyond what are, comparatively speaking, modern. Such are the
sheep and the goat, and such, above all, is our own species. Compared
with many humbler animals, man is a being, as it were, of yesterday.
Thus concludes the wondrous section of the earth's history which is told
by geology. It takes up our globe at an early stage in the formation of
its crust--conducts it through what we have every reason to believe were
vast spaces of time, in the course of which many superficial changes
took place, and vegetable and animal life was gradually evolved--and
drops it just at the point when man was apparently about to enter on the
scene. The compilation of such a history, from materials of so
extraordinary a character, and the powerful nature of the evidence which
these materials afford, are calculated to excite our admiration, and the
result must be allowed to exalt the dignity of science as a product of
man's industry and his reason.
It is now to be remarked that there is nothing in the whole series of
operations displayed in inorganic geology which may not be accounted for
by the agency of the ordinary forces of Nature. Those movements of
subterranean force which thrust up mountain ranges and upheaved
continents stand in inextricable connection, on the one hand, with the
volcanoes which are yet belching forth lavas and shaking large tracts of
ground, as, on the other, with the primitive incandescent state of the
earth. Those forces which disintegrated the early rocks, of which
detritus formed new beds at the bottom of the sea, are still seen at
work to the same effect.
To bring these truths the more nearly before us, it is possible to make
a substance resembling basalt in a furnace; limestone and sandstone have
both been formed from suitable materials in appropriate receptacles; the
phenomena of cleavage have, with the aid of electricity, been simulated
on a small scale, and by the same agent crystals are formed. In short,
the remark which was made regarding the indifference of the cosmical
laws to the scale on which they operated is to be repeated regarding the
geological.
A common furnace will sometimes exemplify the operation of forces which
have produced the Giant's Causeway; and in a sloping ploughed field
after rain we may often observe, at the lower end of a furrow, a handful
of washed and neatly deposited mud or sand, capable of serving as an
illustration of the way in which Nature has produced the deltas of the
Nile and Ganges. In the ripple-marks on sandy beaches of the present day
we see Nature's exact repetition of the operations by which she
impressed similar features on the sandstones of the carboniferous era.
Even such marks as wind-slanted rain would in our day produce on
tide-deserted sands have been read upon tablets of the ancient strata.
It is the same Nature--that is to say, God through or in the manner of
Nature--working everywhere and in all time, causing the wind to blow,
and the rain to fall, and the tide to ebb and flow, inconceivable ages
before the birth of our race, as now. So also we learn from the conifers
of those old ages that there were winter and summer upon earth, before
any of us lived to liken the one to all that is genial in our own
nature, or to say that the other breathed no airs so unkind as man's
ingratitude. Let no one suppose there is any necessary disrespect for
the Creator in thus tracing His laws in their minute and familiar
operations. There is really no true great and small, grand and familiar,
in Nature. Such only appear when we thrust ourselves in as a point from
which to start in judging. Let us pass, if possible, beyond immediate
impressions, and see all in relation to Cause, and we shall chastenedly
admit that the whole is alike worshipful.
The Creator, then, is seen to have formed our earth, and effected upon
it a long and complicated series of changes, in the same manner in which
we find that he conducts the affairs of Nature before our living eyes;
that is, in the manner of natural law. This is no rash or unauthorised
affirmation. It is what we deduce from the calculation of a Newton and a
Laplace on the one hand, and from the industrious observation of facts
by a Murchison and a Lyell on the other. It is a point of stupendous
importance in human knowledge; here at once is the whole region of the
inorganic taken out of the dominion of marvel, and placed under an idea
of Divine regulation.
_III.--The History of the Earth's Life_
Mixed up, however, with the geological changes, and apparently as final
object connected with the formation of the globe itself, there is
another set of phenomena presented in the course of our history--the
coming into existence, namely, of a long suite of living things,
vegetable and animal, terminating in the families which we still see
occupying the surface. The question arises: In what manner has this set
of phenomena originated? Can we touch at and rest for a moment on the
possibility of plants and animals having likewise been produced in a
natural way, thus assigning immediate causes of but one character for
everything revealed to our sensual observation; or are we at once to
reject this idea, and remain content, either to suppose that creative
power here acted in a different way, or to believe unexaminingly that
the inquiry is one beyond our powers? Taking the last question first, I
would reply that I am extremely loth to imagine that there is anything
in Nature which we should, for any reason, refrain from examining. If we
can infer aught from the past history of science, it is that the whole
of Nature is a legitimate field for the exercise of our intellectual
faculties; that there is a connection between this knowledge and our
well-being; and that, if we may judge from things once despaired of by
our inquiring reason, but now made clear and simple, there is none of
Nature's mysteries which we may not hopefully attempt to penetrate. To
remain idly content to presume a various class of immediate causes for
organic Nature seems to me, on this ground, equally objectionable.
With respect to the other question the idea has several times arisen
that some natural course was observed in the production of organic
things, and this even before we were permitted to attain clear
conclusions regarding inorganic nature. It was always set quickly aside
as unworthy of serious consideration. The case is different now, when we
have admitted law in the whole domain of the inorganic.
Otherwise, the absurdities into which we should be led must strike every
reflecting mind. The Eternal Sovereign arranges a solar or an astral
system, by dispositions imparted primordially to matter; he causes, by
the same means, vast oceans to join and continents to rise, and all the
grand meteoric agencies to proceed in ceaseless alternation, so as to
fit the earth for a residence of organic beings. But when, in the course
of these operations, fuci and corals are to be, for the first time,
placed in these oceans, a change in his plan of administration is
required. It is not easy to say what is presumed to be the mode of his
operations. The ignorant believe the very hand of Deity to be at work.
Amongst the learned, we hear of "creative fiats," "interferences,"
"interpositions of the creative energy," all of them very obscure
phrases, apparently not susceptible of a scientific explanation, but all
tending simply to this: that the work was done in a marvellous way, and
not in the way of Nature.
But we need not assume two totally distinct modes of the exercise of the
divine power--one in the course of inorganic nature and the other in
intimately connected course of organic nature.
Indeed, when all the evidence is surveyed, it seems difficult to resist
the impression that vestiges, at least, are seen of the manner and
method of the Creator in this part of His work. It appears to be a case
in which rigid proof is hardly to be looked for. But such evidences as
exist are remarkably consistent and harmonious. The theory pointed to
consorts with everything else which we have learned accurately regarding
the history of the universe. Science has not one positive affirmation on
the other side. Indeed, the view opposed to it is not one in which
science is concerned; it appears as merely one of the prejudices formed
in the non-age of our race.
For the history, then, of organic nature, I embrace, not as a proved
fact, but as a rational interpretation of things as far as science has
revealed them, the idea of progressive development. We contemplate the
simplest and most primitive types of being as giving birth to a type
superior to it; this again producing the next higher, and so on to the
highest. We contemplate, in short, a universal gestation of Nature, like
that of the individual being, and attended as little by circumstances of
a miraculous kind as the silent advance of an ordinary mother from one
week to another of her pregnancy.
Thus simple--after ages of marvelling--appears organic creation, while
yet the whole phenomena are, in another point of view, wonders of the
highest kind, being the undoubted results of ordinances arguing the
highest attributes of foresight, skill and goodness on the part of their
Divine Author.
If, finally, we study the mind of man, we find that its Almighty Author
has destined it, like everything else, to be developed from inherent
qualities.
Thus the whole appears complete on one principle. The masses of space
are formed by law; law makes them in due time theatres of existence for
plants and animals; sensation, disposition, intellect, are all in like
manner sustained in action by law.
It is most interesting to observe into how small a field the whole of
the mysteries of Nature thus ultimately resolve themselves. The
inorganic has been thought to have one final comprehensive
law--gravitation. The organic, the other great department of mundane
things, rests in like manner on one law, and that is--development. Nor
may even these be after all twain, but only branches of one still more
comprehensive law, the expression of a unity flowing immediately from
the One who is first and last.
_IV.--The Future and its Meaning_
The question whether the human race will ever advance far beyond its
present position in intellect and morals is one which has engaged much
attention. Judging from the past, we cannot reasonably doubt that great
advances are yet to be made; but, if the principle of development be
admitted, these are certain, whatever may be the space of time required
for their realisation. A progression resembling development may be
traced in human nature, both in the individual and in large groups of
men. Not only so, but by the work of our thoughtful brains and busy
hands we modify external nature in a way never known before. The
physical improvements wrought by man upon the earth's surface I conceive
as at once preparations for, and causes of, the possible development of
higher types of humanity, beings less strong in the impulsive parts of
our nature, more strong in the reasoning and moral, more fitted for the
delights of social life, because society will then present less to dread
and more to love.
The history and constitution of the world have now been hypothetically
explained, according to the best lights which a humble individual has
found within the reach of his perceptive and reasoning faculties.
We have seen a system in which all is regularity and order, and all
flows from, and is obedient to, a divine code of laws of unbending
operation. We are to understand from what has been laid before us that
man, with his varied mental powers and impulses, is a natural problem of
which the elements can be taken cognisance of by science, and that all
the secular destinies of our race, from generation to generation, are
but evolutions of a law statuted and sustained in action by an all-wise
Deity.
There may be a faith derived from this view of Nature sufficient to
sustain us under all sense of the imperfect happiness, the calamities,
the woes and pains of this sphere of being. For let us but fully and
truly consider what a system is here laid open to view and we cannot
well doubt that we are in the hands of One who is both able and willing
to do us the most entire justice. Surely, in such a faith we may well
rest at ease, even though life should have been to us but a protracted
malady. Thinking of all the contingencies of this world as to be in time
melted into or lost in some greater system, to which the present is only
subsidiary, let us wait the end with patience and be of good cheer.
GEORGES CUVIER
The Surface of the Globe
Georges Cuvier was born Aug. 24, 1769, at Montbéliard, France. He
had a brilliant academic career at Stuttgart Academy, and in 1795,
at the age of twenty-six, he was appointed assistant professor of
comparative anatomy at the Museum d'Histoire Naturelle in Paris,
and was elected a member of the National Institute. From this date
onwards to his death in 1832, his scientific industry was
remarkable. Both as zoologist and palæontologist he must be
regarded as one of the greatest pioneers of science. He filled many
important scientific posts, including the chair of Natural History
in the Collège de France, and a professorship at the Jardin des
Plantes. In 1808 he was made member of the Council of the Imperial
University; and in 1814, President of the Council of Public
Instruction. In 1826 he was made grand officer of the Legion of
Honour, and five years later was made a peer of France. The
"Discours sur les Révolutions de la Surface du Globe," published in
1825, is essentially a preliminary discourse to the author's
celebrated work, "Recherches sur les Ossemens fossiles de
Quadrupèdes." It is an endeavour to trace the relationship between
the changes which have taken place on the surface of the globe and
the changes which have taken place in its animal inhabitants, with
especial reference to the evidence afforded by fossil remains of
quadrupeds. "It is apparent," Cuvier writes, "that the bones of
quadrupeds conduct us, by various reasonings, to more precise
results than any other relics of organised bodies." The two books
together may be considered the first really scientific
palæontology.
_I.--Effects of Geological Change_
My first object will be to show how the fossil remains of the
terrestrial animals are connected with the theory of the earth. I shall
afterwards explain the principles by which fossil bones may be
identified. I shall give a rapid sketch of new species discovered by the
application of these principles. I shall then show how far these
varieties may extend, owing to the influence of the climate and
domestication. I shall then conceive myself justified in concluding that
the more considerable differences which I have discovered are the
results of very important catastrophes. Afterwards I shall explain the
peculiar influence which my researches should exercise on the received
opinions concerning the revolutions of the globe. Finally, I shall
examine how far the civil and religious history of nations accords with
the results of observation on the physical history of the earth.
When we traverse those fertile plains, where tranquil waters cherish, as
they flow, an abundant vegetation, and where the soil, trod by a
numerous people, adorned with flourishing villages, rich cities, and
superb monuments, is never disturbed save by the ravages of war, or the
oppression of power, we can hardly believe that Nature has also had her
internal commotions. But our opinions change when we dig into this
apparently peaceful soil, or ascend its neighboring hills. The lowest
and most level soils are composed of horizontal strata, and all contain
marine productions to an innumerable extent. The hills to a very
considerable height are composed of similar strata and similar
productions. The shells are sometimes so numerous as to form the entire
mass of the soil, and all quarters of the globe exhibit the same
phenomenon.
The time is past when ignorance could maintain that these remains of
organised bodies resulted from the caprice of Nature, and were
productions formed in the bosom of the earth by its generative powers;
for a scrupulous comparison of the remains shows not the slightest
difference between the fossil shells and those that are now found in the
ocean. It is clear, then, that they inhabited the sea, and that they
were deposited by the sea in the places where they are now found; and it
follows, too, that the sea rested in these places long enough to form
regular, dense, vast deposits of aquatic animals.
The bed of the sea, accordingly, must have undergone some change either
in extent or situation.
Further, we find under the horizontal strata, _inclined_ strata. Thus
the sea, previously to the formation of the horizontal strata, must have
formed others, which have been broken, inclined, and overturned by some
unknown causes.
More than this, we find that the fossils vary with the depth of the
strata, and that the fossils of the deeper and more ancient strata
exhibit a formation proper to themselves; and we find in some of the
strata, too, remains of terrestrial life.
The evidence is thus plain that the animal life in the sea has varied,
and that parts of the earth's surface have been alternately dry land and
ocean. The very soil, which terrestrial animals at present inhabit has a
history of previous animal life, and then submersion under the sea.
The reiterated irruptions and retreats of the sea have not all been
gradual, but, on the contrary, they have been produced by sudden
catastrophes. The last catastrophe, which inundated and again left dry
our present continents, left in the northern countries the carcasses of
large quadrupeds, which were frozen, and which are preserved even to the
present day, with their skin, hair and flesh. Had they not been frozen
the moment they were killed, they must have putrefied; and, on the other
hand, the intense frost could not have been the ordinary climatic
condition, for they could not have existed at such low temperatures. In
the same instant, then, in which these animals perished the climate
which they inhabited must have undergone a complete revolution.
The ruptures, the inclinations, the overturnings of the more ancient
strata, likewise point to sudden and violent changes.
Animal life, then, has been frequently disturbed on this earth by
terrific catastrophes. Living beings innumerable have perished. The
inhabitants of the dry land have been engulfed by deluges; and the
tenants of the water, deserted by their element, have been left to
perish from drought.
Even ancient rocks formed or deposited before the appearance of life on
the earth show signs of terrific violence.
It has been maintained by some that the causes now at work altering the
face of the world are sufficient to account for all the changes through
which it has passed: but that is not so. None of the agents Nature now
employs--rain, thaw, rivers, seas, volcanoes--would have been adequate
to produce her ancient works.
To explain the external crust of the world, we require causes other than
those present in operation, and a thousand extraordinary theories have
been advanced. Thus, according to one philosopher, the earth has
received in the beginning a uniform light crust which caused the abysses
of the ocean, and was broken to produce the Deluge. Another supposed the
Deluge to be caused by the momentary suspension of the cohesion of
minerals.
Even accomplished scientists and philosophers have advanced impossible
and contradictory theories.
All attempts at explanation have been stultified by an ignorance of the
facts to be explained, or by a partial survey of them, and especially by
a neglect of the evidence afforded by fossils. How was it possible not
to perceive that the theory of the earth owes its origin to fossils
alone? They alone, in truth, inform us with any certainty that the earth
has not always had the same covering, since they certainly must have
lived upon its surface before they were buried in its depths. If there
were only strata without fossils, one might maintain that the strata had
all been formed together. Hitherto, in fact, philosophers have been at
variance on every point save one, and that is that the sea has changed
its bed; and how could this have been known except for fossils?
From this consideration I was led to study fossils; and since the field
was immense I was obliged to specialise in one department of fossils,
and selected for study the fossil bones of quadrupeds. I made this
selection because only from a study of fossil quadrupeds can one hope to
ascertain the number and periods and contents of irruptions of the sea;
and because, since the number of quadrupeds is limited, and most
quadrupeds known, we have better means of assuring ourselves if the
fossil remains are remains of extinct or extant animals. Animals such as
the griffin, the cartazonon, the unicorn, never lived, and there are
probably very few quadrupeds now living which have not been found by
man.
But though the study of fossil quadruped be enlightening, it has its own
special difficulties. One great difficulty arises from the fact that it
is very rare to find a fossil skeleton approaching to a complete state.
Fortunately, however, there is a principle in comparative anatomy which
lessens this difficulty. Every organised being constitutes a complete
and compact system with all its parts in mutual correspondence. None of
its parts can be changed without changing other parts, and consequently
each part, taken separately, indicates the others.
Thus, if the intestines of an animal are made to digest raw flesh, its
jaws must be likewise constructed to devour prey, its claws to seize and
tear it, its teeth to rend it, its limbs to overtake it, its organs of
sense to discern it afar. Again, in order to enable the jaw to seize
with facility, a certain form of condyle is necessary, and the zygomatic
arch must be well developed to give attachment to the masseter muscle.
Again, the muscles of the neck must be powerful, whence results a
special form in the vertebræ and the occiput, where the muscles are
attached. Yet again, in order that the claws may be effective, the
toe-bones must have a certain form, and must have muscles and tendons
distributed in a certain way. In a word, the form of the tooth
necessitates the form of the condyle, of the shoulder-blade, and of the
claws, of the femur, and of all the other bones, and all the other bones
taken separately will give the tooth. In this manner anyone who is
scientifically acquainted with the laws of organic economy may from a
fragment reconstruct the whole animal. The mark of a cloven hoof is
sufficient to tell the form of the teeth and jaws and vertebræ and
leg-bones and thigh-bones and pelvis of the animal. The least fragment
of bone, the smallest apophysis, has a determinative character in
relation to the class, the order, the genus, and species to which it may
belong. This is so true that, if we have only a single extremity of bone
well preserved, we may, with application and a skilful use of analogy
and exact comparison, determine all those points with as much certainty
as if we were in possession of the entire animal. By the application of
these principles we have identified and classified the fossil remains of
more than one hundred and fifty mammalia.
_II.--What the Fossils Teach_
An examination of the fossils on the lines I have indicated shows that
out of one hundred and fifty mammiferous and oviparous quadrupeds,
ninety are unknown to present naturalists, and that in the older layers
such oviparous quadrupeds as the ichthyosauri and plesiosauri abound.
The fossil elephant, the rhinoceros, the hippopotamus, and the mastodons
are not found in the more ancient layers. In fact, the species which
appear the same as ours are found only in superficial deposits.
Now, it cannot be held that the present races of animals differ from
the ancient races merely by modifications produced by local
circumstances and change of climate--for if species gradually changed,
we must find traces of these gradual modifications, and between the
palæotheria and the present species we should have discovered some
intermediate formation; but to the present time none of these have
appeared.
Why have not the bowels of the earth preserved the monuments of so
remarkable a genealogy unless it be that the species of former ages were
as constant as our own, or at least because the catastrophe that
destroyed them had not left them time to give evidence of the changes?
Further, an examination of animals shows that though their superficial
characteristics, such as colour and size, are changeable, yet their more
radical characteristics do not change. Even the artificial breeding of
domestic animals can produce only a limited degree of variation. The
maximum variation known at the present time in the animal kingdom is
seen in dogs, but in all the varieties the relations of the bones remain
the same and the shape of the teeth undergoes no palpable change.
I know that some naturalists rely much on the thousands of ages which
they can accumulate with a stroke of the pen; but there is nothing which
proves that time will effect any more than climate and a state of
domestication. I have endeavoured to collect the most ancient documents
of the forms of animals. I have examined the engravings of animals
including birds on the numerous columns brought from Egypt to Rome. M.
Saint Hilaire collected all the mummies of animals he could obtain in
Egypt--cats, ibises, birds of prey, dogs, monkeys, crocodiles, etc.--and
we cannot find any more difference between them and those of the present
day than between human mummies of that date and skeletons of the present
day.
There is nothing, then, in known facts which can support the opinion
that the new genera discovered among fossils--the palæotheria,
anoplotheria, megalonyces, mastodontes, pterodactyli, ichthyosauri,
etc.--could have been the sources of any animals now existing, which
would differ only by the influence of time or climate.
As yet no human bones have been discovered in the regular layers of the
surface of the earth, so that man probably did not exist in the
countries where fossil bones are found at the epoch of the revolutions
which buried these bones, for there cannot be assigned any reason why
mankind should have escaped such overwhelming catastrophes, or why human
remains should not be discovered. Man _may_ have inhabited some confined
tract of country which escaped the catastrophe, but his establishment in
the countries where the fossil remains of land animals are found--that
is to say, in the greatest part of Europe, Asia, and America--is
necessarily posterior not only to the revolutions which covered these
bones, but even to those which have laid open the strata which envelop
them; whence it is clear that we can draw neither from the bones
themselves nor from the rocks which cover them any argument in favour of
the antiquity of the human species in these different countries. On the
contrary, in closely examining what has taken place on the surface of
the globe, since it was left dry for the last time, we clearly see that
the last revolution, and consequently the establishment of present
society, cannot be very ancient. An examination of the amount of
alluvial matter deposited by rivers, of the progress of downs, and of
other changes on the surface of the earth, informs us clearly that the
present state of things did not commence at a very remote period.
The history of nations confirms the testimony of the fossils and of the
rocks. The chronology of none of the nations of the West can be traced
unbroken farther back than 3,000 years. The Pentateuch, the most ancient
document the world possesses, and all subsequent writings allude to a
universal deluge, and the Pentateuch and Vedas and Chou-king date this
catastrophe as not more than 5,400 years before our time. Is it possible
that mere chance gave a result so striking as to make the traditional
origin of the Assyrian, Indian, and Chinese monarchies agree in being as
remote as 4,000 or 5,000 years back? Would the ideas of nations with so
little inter-communication, whose language, religion, and laws have
nothing in common, agree on this point if they were not founded on
truth? Even the American Indians have their Noah or Deucalion, like the
Indians, Babylonians, and Greeks.
It may be said that the long existence of ancient nations is attested by
their progress in astronomy. But this progress has been much
exaggerated. But what would this astronomy prove even if it were more
perfect? Have we calculated the progress which a science would make in
the bosom of nations which had no other? If among the multitude of
persons solely occupied with astronomy, even then, all that these people
knew might have been discovered in a few centuries, when only 300 years
intervened between Copernicus and Laplace.
Again, it has been pretended that the zodiacal figures on ancient
temples give proof of a remote antiquity; but the question is very
complicated, and there are as many opinions as writers, and certainly no
conclusions against the newness of continents and nations can be based
on such evidence. The zodiac itself has been considered a proof of
antiquity, but the arguments brought forward are undoubtedly unsound.
Even if these various astronomical proofs were as certain as they are
unconvincing, what conclusion could we draw against the great
catastrophe so indisputably demonstrated? We should only have the right
to conclude that astronomy was among the sciences preserved by those
persons whom the catastrophe spared.
In conclusion, if there be anything determined in geology, it is that
the surface of our globe has been subjected to a revolution within 5,000
years, and that this revolution buried the countries formerly inhabited
by man and modern animals, and left the bottom of the former sea dry as
a habitation for the few individuals it spared. Consequently, our
present human societies have arisen since this catastrophe.
But the countries now inhabited had been inhabited before, as fossils
show, by animals, if not by mankind, and had been overwhelmed by a
previous deluge; and, indeed, judging by the different orders of animal
fossils we find, they had perhaps undergone two or three irruptions of
the sea.
CHARLES DARWIN
The Origin of Species
Charles Robert Darwin was born at Shrewsbury, England, Feb. 12,
1809, of a family distinguished on both sides. Abandoning medicine
for natural history, he joined H.M.S. Beagle in 1831 on the five
years' voyage, which he described in "The Voyage of the Beagle,"
and to which he refers in the introduction to his masterpiece. The
"Origin of Species" containing, in the idea of natural selection,
the distinctive contribution of Darwin to the theory of organic
evolution, was published in November, 1859. In only one brief
sentence did he there allude to man, but twelve years later he
published the "Descent of Man," in which the principles of the
earlier volume found their logical outcome. In other works Darwin
added vastly to our knowledge of coral reefs, organic variation,
earthworms, and the comparative expression of the emotions in man
and animals. Darwin died in ignorance of the work upon variation
done by his great contemporary, Gregor Mendel, whose work was
rediscovered in 1900. "Mendelism" necessitates much modification of
Darwin's work, which, however, remains the maker of the greatest
epoch in the study of life and the most important contribution to
that study ever made. Its immortal author died on April 19, 1882,
and was buried in Westminster Abbey.
_I.--Creation or Evolution?_
When on board H.M.S. Beagle as naturalist, I was much struck with
certain facts in the distribution of the organic beings inhabiting South
America, and in the geographical relations of the present to the past
inhabitants of that continent. These facts, as will be seen in the
latter chapters of this volume, seemed to throw some light on the origin
of species--that mystery of mysteries, as it has been called by one of
our greatest philosophers. On my return home, in 1837, it occurred to me
that something might perhaps be made out on this question by patiently
accumulating and reflecting on all sorts of facts which could possibly
have any bearing on it. After five years' work, I allowed myself to
speculate on the subject, and drew up some short notes; these I enlarged
in 1844 into a sketch of the conclusions which then seemed to me
probable. From that period to the present day I have steadily pursued
the same object. I hope that I may be excused for entering on these
personal details, as I give them to show that I have not been hasty in
coming to a decision.
In considering the origin of species, it is quite conceivable that a
naturalist, reflecting on the mutual affinities of organic beings, on
their embryological relations, their geographical distribution,
geological succession, and other such facts, might come to the
conclusion that species had not been independently created, but had
descended, like varieties, from other species. Nevertheless, such a
conclusion, even if well founded, would be unsatisfactory, until it
could be shown how the innumerable species inhabiting this world have
been modified so as to acquire that perfection of structure and
co-adaptation which justly excites our admiration.
Naturalists continually refer to external conditions, such as climate,
food, etc., as the only possible cause of variation. In one limited
sense, as we shall hereafter see, this may be true; but it is
preposterous to attribute to mere external conditions the structure, for
instance, of the woodpecker, with its feet, tail, beak, and tongue, so
admirably adapted to catch insects under the bark of trees. In the case
of the mistletoe, which draws its nourishment from certain trees, which
has seeds that must be transported by certain birds, and which has
flowers with separate sexes absolutely requiring the agency of certain
insects to bring pollen from one flower to the other, it is equally
preposterous to account for the structure of the parasite, with its
relations to several distinct organic beings, by the effects of external
conditions, or of habit, or of the volition of the plant itself.
It is, therefore, of the highest importance to gain a clear insight into
the means of modification and co-adaptation. At the beginning of my
observations it seemed to me probable that a careful study of
domesticated animals and of cultivated plants would offer the best
chance of making out this obscure problem. Nor have I been disappointed;
in this and in all other perplexing cases I have invariably found that
our knowledge, imperfect though it be, of variation under domestication,
afforded the best and safest clue. I may venture to express my
conviction of the high value of such studies, although they have been
very commonly neglected by naturalists.
Although much remains obscure, and will long remain obscure, I can
entertain no doubt, after the most deliberate study and dispassionate
judgment of which I am capable, that the view which most naturalists
until recently entertained, and which I formerly entertained--namely,
that each species has been independently created--is erroneous. I am
fully convinced that species are not immutable, but that those belonging
to what are called the same genera are lineal descendants of some other
and generally extinct species, in the same manner as the acknowledged
varieties of any one species are the descendants of that species.
Furthermore, I am also convinced that Natural Selection has been the
most important, but not the exclusive, means of modification.
_II.--Variation and Selection_
All living beings vary more or less from one another, and though
variations which are not inherited are unimportant for us, the number
and diversity of inheritable deviations of structure, both those of
slight and those of considerable physiological importance, are endless.
No breeder doubts how strong is the tendency to inheritance; that like
produces like is his fundamental belief. Doubts have been thrown on
this principle only by theoretical writers. When any deviation of
structure often appears, and we see it in the father and child, we
cannot tell whether it may not be due to the same cause having acted on
both; but when amongst individuals, apparently exposed to the same
conditions, any very rare deviation, due to some extraordinary
combination of circumstances, appears in the parent--say, once amongst
several million individuals--and it re-appears in the child, the mere
doctrine of chances almost compels us to attribute its reappearance to
inheritance.
Everyone must have heard of cases of albinism, prickly skin, hairy
bodies, etc., appearing in members of the same family. If strange and
rare deviations of structure are really inherited, less strange and
commoner deviations may be freely admitted to be inheritable. Perhaps
the correct way of viewing the whole subject would be to look at the
inheritance of every character whatever as the rule, and non-inheritance
as the anomaly.
The laws governing inheritance are for the most part unknown. No one can
say why the same peculiarity in different individuals of the same
species, or in different species, is sometimes inherited and sometimes
not so; why the child often reverts in certain characters to its
grandfather or grandmother, or more remote ancestor; why a peculiarity
is often transmitted from one sex to both sexes, or to one sex alone,
more commonly but not exclusively to the like sex.
The fact of heredity being given, we have evidence derived from human
practice as to the influence of selection. There are large numbers of
domesticated races of animals and plants admirably suited in various
ways to man's use or fancy--adapted to the environment of which his need
and inclination are the most essential constituents. We cannot suppose
that all the breeds were suddenly produced as perfect and as useful as
we now see them; indeed, in many cases, we know that this has not been
their history. The key is man's power of accumulative selection. Nature
gives successive variations; man adds them up in certain directions
useful to him. In this sense he may be said to have made for himself
useful breeds.
The great power of this principle of selection is not hypothetical. It
is certain that several of our eminent breeders have, even within a
single lifetime, modified to a large extent their breeds of cattle and
sheep. What English breeders have actually effected is proved by the
enormous prices given for animals with a good pedigree; and these have
been exported to almost every quarter of the world. The same principles
are followed by horticulturists, and we see an astonishing improvement
in many florists' flowers, when the flowers of the present day are
compared with drawings made only twenty or thirty years ago.
The practice of selection is far from being a modern discovery. The
principle of selection I find distinctly given in an ancient Chinese
encyclopædia. Explicit rules are laid down by some of the Roman
classical writers. It is clear that the breeding of domestic animals was
carefully attended to in ancient times, and is now attended to by the
lowest savages. It would, indeed, have been a strange fact had attention
not been paid to breeding, for the inheritance of good and bad qualities
is so obvious.
Study of the origin of our domestic races of animals and plants leads to
the following conclusions. Changed conditions of life are of the highest
possible importance in causing variability, both by acting directly on
the organisation, and indirectly by affecting the reproductive system.
Spontaneous variation of unknown origin plays its part. Some, perhaps a
great, effect may be attributed to the increased use or disuse of parts.
The final result is thus rendered infinitely complex. In some cases the
intercrossing of aboriginally distinct species appears to have played
an important part in the origin of our breeds. When several breeds have
once been formed in any country, their occasional intercrossing, with
the aid of selection, has, no doubt, largely aided in the formation of
new sub-breeds; but the importance of crossing has been much
exaggerated, both in regard to animals and to those plants which are
propagated by seed. Over all these causes of change, the accumulative
action of selection, whether applied methodically and quickly, or
unconsciously and slowly, but more efficiently, seems to have been the
predominant power.
_III.--Variation Under Nature_
Before applying these principles to organic beings in a state of nature,
we must ascertain whether these latter are subject to any variation. We
find variation everywhere. Individual differences, though of small
interest to the systematist, are of the highest importance for us, for
they are often inherited; and they thus afford materials for natural
selection to act and accumulate, in the same manner as man accumulates
in any given direction individual differences in his domesticated
productions. Further, what we call varieties cannot really be
distinguished from species in the long run, a fact which we can clearly
understand if species once existed as varieties, and thus originated.
But the facts are utterly inexplicable if species are independent
creations.
How have all the exquisite adaptations of one part of the body to
another part, and to the conditions of life, and of one organic being to
another being, been perfected? For everywhere we find these beautiful
adaptations.
The answer is to be found in the struggle for life. Owing to this
struggle, variations, however slight, and from whatever cause
proceeding, if they be in any degree profitable to the individuals of a
species in their infinitely complex relations to other organic beings
and to their physical conditions of life, will tend to the preservation
of such individuals, and will generally be inherited by the offspring.
The offspring, also, will thus have a better chance of surviving, for,
of the many individuals of any species which are periodically born, but
a small number can survive. I have called this principle, by which each
slight variation, if useful, is preserved, by the term Natural
Selection, in order to mark its relation to man's power of selection.
But the expression, often used by Mr. Herbert Spencer, of the Survival
of the Fittest, is more accurate.
We have seen that man, by selection, can certainly produce great
results, and can adapt organic beings to his own uses, through the
accumulation of slight but useful variations given to him by the hand of
Nature. Natural Selection is a power incessantly ready for action, and
is as immeasurably superior to man's feeble efforts as the works of
Nature are to those of Art.
All organic beings are exposed to severe competition. Nothing is easier
than to admit in words the truth of the universal struggle for life, or
more difficult--at least, I have found it so--than constantly to bear
this conclusion in mind. Yet, unless it be thoroughly engrained in the
mind, the whole economy of Nature, with every fact of distribution,
rarity, abundance, extinction, and variation, will be dimly seen or
quite misunderstood. We behold the face of Nature bright with gladness;
we often see superabundance of food. We do not see, or we forget, that
the birds which are idly singing round us mostly live on insects or
seeds, and are thus constantly destroying life; or we forget how largely
these songsters, or their eggs, or their nestlings, are destroyed by
birds or beasts of prey. We do not always bear in mind that, though food
may be superabundant, it is not so at all seasons of each recurring
year.
A struggle for existence, the term being used in a large, general, and
metaphorical sense, inevitably follows from the high rate at which all
organic beings tend to increase.
Every being, which during its natural lifetime produces several eggs or
seeds, must suffer destruction during some period of its life, and
during some season or occasional year; otherwise, on the principle of
geometrical increase, its numbers would quickly become so inordinately
great that no country could support the product. Hence, as more
individuals are produced than can possibly survive, there must in every
case be a struggle for existence, either one individual with another of
the same species, or with the individuals of distinct species, or with
the physical conditions of life. It is the doctrine of Malthus applied
with manifold force to the whole animal and vegetable kingdoms; for in
this case there can be no artificial increase of food, and no prudential
restraint from marriage. Although some species may be now increasing,
more or less rapidly, in numbers, all cannot do so, for the world would
not hold them.
There is no exception to the rule that every organic being naturally
increases at so high a rate that, if not destroyed, the earth would soon
be covered by the progeny of a single pair. Even slow-breeding man has
doubled in twenty-five years, and at this rate, in less than a thousand
years, there would literally not be standing-room for his progeny.
Linnæus has calculated that if an annual plant produced only two
seeds--and there is no plant so unproductive as this--and their
seedlings next year produced two, and so on, then in twenty years there
would be a million plants. The elephant is reckoned the slowest breeder
of all known animals, and I have taken some pains to estimate its
probable minimum rate of natural increase. It will be safest to assume
that it begins breeding when thirty years old, and goes on breeding
until ninety years old, bringing forth six young in the interval, and
surviving till one hundred years old. If this be so, after a period of
from 740 to 750 years there would be nearly nineteen million elephants
alive, descended from the first pair.
The causes which check the natural tendency of each species to increase
are most obscure. Eggs or very young animals seem generally to suffer
most, but this is not invariably the case. With plants there is a vast
destruction of seeds. The amount of food for each species of course
gives the extreme limit to which each can increase; but very frequently
it is not the obtaining food, but the serving as prey to other animals,
which determines the average number of a species. Climate is important,
and periodical seasons of extreme cold or drought seem to be the most
effective of all checks.
The relations of all animals and plants to each other in the struggle
for existence are most complex, and often unexpected. Battle within
battle must be continually recurring with varying success; and yet in
the long run the forces are so nicely balanced that the face of Nature
remains for long periods of time uniform, though assuredly the merest
trifle would give the victory to one organic being over another.
Nevertheless, so profound is our ignorance, and so high our presumption,
that we marvel when we hear of the extinction of an organic being; and
as we do not see the cause, we invoke cataclysms to desolate the world,
or invent laws on the duration of the forms of life!
The struggle for life is most severe between individuals and varieties
of the same species. The competition is most severe between allied forms
which fill nearly the same place in the economy of Nature. But great is
our ignorance on the mutual relations of all organic beings. All that we
can do is to keep steadily in mind that each organic being is striving
to increase in a geometrical ratio; that each at some period of its
life, during some season of the year, during each generation or at
intervals, has to struggle for life and to suffer great destruction.
When we reflect on this struggle, we may console ourselves with the full
belief that the war of Nature is not incessant, that no fear is felt,
that death is generally prompt, and that the vigorous, the healthy, and
the happy survive and multiply.
_IV.--The Survival of the Fittest_
How will the struggle for existence act in regard to variation? Can the
principle of selection, which we have seen is so potent in the hands of
man, apply under Nature? I think we shall see that it can act most
efficiently. Let the endless number of slight variations and individual
differences occurring in our domestic productions, and, in a lesser
degree, in those under Nature, be borne in mind, as well as the strength
of the hereditary tendency. Under domestication, it may be truly said
that the whole organisation becomes in some degree plastic.
But the variability, which we almost universally meet with in our
domestic productions, is not directly produced by man; he can neither
originate variations nor prevent their occurrence; he can only preserve
and accumulate such as do occur. Unintentionally he exposes organic
beings to new and changing conditions of life, and variability ensues;
but similar changes of condition might and do occur under Nature.
Let it also be borne in mind how infinitely complex and close-fitting
are the mutual relations of all organic beings to each other and to
their physical conditions of life, and consequently what infinitely
varied diversities of structure might be of use to each being under
changing conditions of life. Can it, then, be thought improbable, seeing
what variations useful to man have undoubtedly occurred, that other
variations, useful in some way to each being in the great complex battle
of life, should occur in the course of many successive generations? If
such do occur, can we doubt, remembering that many more individuals are
born than can possibly survive, that individuals having any advantage
over others, would have the best chance of surviving and of procreating
their kind? On the other hand, we may feel sure that any variation in
the least degree injurious would be rigidly destroyed. This preservation
of favourable individual differences and variations, and the destruction
of those which are injurious, I have called Natural Selection, or the
Survival of the Fittest.
The term is too frequently misapprehended. Variations neither useful nor
injurious would not be affected by natural selection. It is not asserted
that natural selection induces variability. It implies only the
preservation of such varieties as arise and are beneficial to the being
under its conditions of life. Again, it has been said that I speak of
natural selection as an active Power or Deity; but who objects to an
author speaking of the attraction of gravity as ruling the movements of
the planets? It is difficult to avoid personifying the word Nature; but
I mean by Nature only the aggregate action and product of many natural
laws, and by laws the sequence of events as ascertained by us.
As man can produce, and certainly has produced, a great result by his
methodical and unconscious means of selection, what may not natural
selection effect? Man can act only on external and visible characters;
Nature, if I may be allowed to personify the natural preservation or
survival of the fittest, cares nothing for appearances, except in so far
as they are useful to any being. She can act on every internal organ, on
every shade of constitutional difference, on the whole machinery of
life. Man selects only for his own good; Nature only for that of the
being which she tends. Every selected character is fully exercised by
her, as is implied by the fact of their selection. Man keeps the natives
of many climates in the same country; he seldom exercises each selected
character in some peculiar and fitting manner; he feeds a long and a
short-beaked pigeon on the same food; he does not exercise a long-backed
or long-legged quadruped in any peculiar manner; he exposes sheep with
long and short wool to the same climate.
Man does not allow the most vigorous males to struggle for the females.
He does not rigidly destroy all inferior animals, but protects during
each varying season, as far as lies in his power, all his productions.
He often begins his selection by some half-monstrous form; or at least
by some modification prominent enough to catch the eye or to be plainly
useful to him.
But under Nature, the slightest differences of structure or constitution
may well turn the nicely-balanced scale in the struggle for life, and so
be preserved. How fleeting are the wishes and efforts of man! How short
his time! And, consequently, how poor will be his results compared with
those accumulated by Nature during whole geological periods! Can we
wonder that Nature's productions should be far "truer" in character than
man's productions; that they should be infinitely better adapted to the
most complex conditions of life, and should plainly bear the stamp of
far higher workmanship?
It may metaphorically be said that natural selection is daily and hourly
scrutinising, throughout the world, the slightest variations; rejecting
those that are bad, preserving and adding up all that are good; silently
and insensibly working, whenever and wherever opportunity offers, at the
improvement of each organic being in relation to its organic and
inorganic conditions of life. We see nothing of these slow changes in
progress until the hand of time has marked the lapse of ages, and then
so imperfect is our view into long-past geological ages that we see only
that the forms of life are now different from what they formerly were.
Although natural selection can act only through and for the good of
each being, yet characters and structures, which we are apt to consider
as of very trifling importance, may thus be acted on.
Natural selection will modify the structure of the young in relation to
the parent, and of the parent in relation to the young. In social
animals it will adapt the structure of each individual for the benefit
of the whole community, if the community profits by the selected change.
What natural selection cannot do is to modify the structure of one
species, without giving it any advantage, for the good of another
species; and though statements to this effect may be found in works of
natural history, I cannot find one case which will bear investigation.
A structure used only once in an animal's life, if of high importance to
it, might be modified to any extent by natural selection; for instance,
the great jaws possessed by certain insects, used exclusively for
opening the cocoon, or the hard tip to the beak of unhatched birds, used
for breaking the egg. It has been asserted that of the best short-beaked
tumbler pigeons a greater number perish in the egg than are able to get
out of it; so that fanciers assist in the act of hatching. Now, if
Nature had to make the beak of a full-grown pigeon very short for the
bird's own advantage, the process of modification would be very slow,
and there would be simultaneously the most rigorous selection of all the
young birds within the egg, for all with weak beaks would inevitably
perish; or more easily broken shells might be selected, the thickness of
the shell being known to vary like every other structure.
With all beings there must be much fortuitous destruction, which can
have little or no influence on the course of natural selection. For
instance, a vast number of eggs or seeds are annually devoured, and
these could be modified through natural selection only if they varied
in some manner which protected them from their enemies. Yet many of
these eggs or seeds would perhaps, if not destroyed, have yielded
individuals better adapted to their conditions of life than any of those
which happened to survive. So, again, a vast number of mature animals
and plants, whether or not they be the best adapted to their conditions,
must be annually destroyed by accidental causes, which would not be in
the least degree mitigated by certain changes of structure or
constitution which would in other ways be beneficial to the species.
But let the destruction of the adults be ever so heavy, if the number
which can exist in any district be not wholly kept down by such
causes--or, again, let the destruction of eggs or seeds be so great that
only a hundredth or a thousandth part are developed--yet of those which
do survive, the best adapted individuals, supposing there is any
variability in a favourable direction, will tend to propagate their kind
in larger numbers than the less well adapted.
On our theory the continued existence of lowly organisms offers no
difficulty; for natural selection does not necessarily include
progressive development; it only takes advantage of such variations as
arise and are beneficial to each creature under its complex relations of
life.
The mere lapse of time by itself does nothing, either for or against
natural selection. I state this because it has been erroneously asserted
that the element of time has been assumed by me to play an all-important
part in modifying species, as if all the forms of life were necessarily
undergoing change through some innate law.
_V.--Sexual Selection_
This form of selection depends, not on a struggle for existence in
relation to other organic beings or to external conditions, but on a
struggle between the individuals of one sex, generally the males, for
the possession of the other sex. The result is not death to the
unsuccessful competitor, but few or no offspring. Sexual selection is,
therefore, less rigorous than natural selection. Generally, the most
vigorous males, those which are best fitted for their places in Nature,
will leave most progeny. But, in many cases, victory depends not so much
on general vigour as on having special weapons, confined to the male
sex. A hornless stag or spurless cock would have a poor chance of
leaving numerous offspring. Sexual selection, by always allowing the
victor to breed, might surely give indomitable courage, length to the
spur, and strength to the wing to strike in the spurred leg, in nearly
the same manner as does the brutal cock-fighter by the careful selection
of his best cocks.
How low in the scale of Nature the law of battle descends I know not.
Male alligators have been described as fighting, bellowing, and whirling
round, like Indians in a war-dance, for the possession of the females;
male salmons have been observed fighting all day long; male stag-beetles
sometimes bear wounds from the mandibles of other males; the males of
certain other insects have been frequently seen fighting for a
particular female who sits by, an apparently unconcerned beholder of the
struggle, and then retires with the conqueror. The war is, perhaps,
severest between the males of the polygamous animals, and these seem
oftenest provided with special weapons. The males of carnivorous animals
are already well armed, though to them special means of defence may be
given through means of sexual selection, as the mane of the lion and the
hooked jaw of the salmon. The shield may be as important for victory as
the sword or spear.
Amongst birds, the contest is often of a more peaceful character. All
those who have attended to the subject believe that there is the
severest rivalry between the males of many species to attract, by
singing, the females. The rock-thrush of Guiana, birds of paradise, and
some others, congregate; and successive males display with the most
elaborate care, and show off in the best manner, their gorgeous plumage;
they likewise perform strange antics before the females, which, standing
by as spectators, at last choose the most attractive partner.
If man can in a short time give beauty and an elegant carriage to his
bantams, according to his standard of beauty, I can see no good reason
to doubt that female birds, by selecting, during thousands of
generations, the most melodious or beautiful males, according to their
standard of beauty, might produce a marked effect.
_VI.--The Struggle for Existence_
Under domestication we see much variability, caused, or at least
excited, by changed conditions of life; but often in so obscure a manner
that we are tempted to consider the variations as spontaneous.
Variability is governed by many complex laws--by correlated growth,
compensation, the increased use and disuse of parts, and the definite
action of the surrounding conditions. There is much difficulty in
ascertaining how largely our domestic productions have been modified;
but we may safely infer that the amount has been large, and that
modifications can be inherited for long periods. As long as the
conditions of life remain the same, we have reason to believe that a
modification, which has already been inherited for many generations, may
continue to be inherited for an almost infinite number of generations.
On the other hand, we have evidence that variability, when it has once
come into play, does not cease under domestication for a very long
period; nor do we know that it ever ceases, for new varieties are still
occasionally produced by our oldest domesticated productions.
Variability is not actually caused by man; he only unintentionally
exposes organic beings to new conditions of life, and then Nature acts
on the organisation and causes it to vary. But man can and does select
the variations given to him by Nature, and thus accumulates them in any
desired manner. He thus adapts animals and plants for his own benefit or
pleasure. He may do this methodically, or he may do it unconsciously by
preserving the individuals most useful or pleasing to him without an
intention of altering the breed.
It is certain that he can influence the character of a breed by
selecting, in each successive generation, individual differences so
slight as to be inappreciable except by an educated eye. This
unconscious process of selection has been the agency in the formation of
the most distinct and useful domestic breeds. That many breeds produced
by man have to a large extent the character of natural species is shown
by the inextricable doubts whether many of them are varieties or
aboriginally distinct species.
There is no reason why the principles which have acted so efficiently
under domestication should not have acted under Nature. In the survival
of favoured individuals and races, during the constantly recurrent
struggle for existence, we see a powerful and ever-acting form of
selection. The struggle for existence inevitably follows from the high
geometrical ratio of increase which is common to all organic beings.
This high rate of increase is proved by calculation; by the rapid
increase of many animals and plants during a succession of peculiar
seasons and when naturalised in new countries. More individuals are born
than can possibly survive. A grain in the balance may determine which
individuals shall live and which shall die; which variety or species
shall increase in number, and which shall decrease, or finally become
extinct.
As the individuals of the same species come in all respects into the
closest competition with each other, the struggle will generally be
most severe between them; it will be almost equally severe between the
varieties of the same species, and next in severity between the species
of the same genus. On the other hand, the struggle will often be severe
between beings remote in the scale of Nature. The slightest advantage in
certain individuals, at any age or during any season, over those with
which they come into competition, or better adaptation, in however
slight a degree, to the surrounding physical conditions, will, in the
long run, turn the balance.
With animals having separated sexes, there will be in most cases a
struggle between the males for the possession of the females. The most
vigorous males, or those which have most successfully struggled with
their conditions of life, will generally leave most progeny. But success
will often depend on the males having special weapons, or means of
defence, or charms; and a slight advantage will lead to victory.
As geology plainly proclaims that each land has undergone great physical
changes, we might have expected to find that organic beings have varied
under Nature in the same way as they have varied under domestication.
And if there has been any variability under Nature, it would be an
unaccountable fact if natural selection had not come into play. It has
often been asserted, but the assertion is incapable of proof, that the
amount of variation under Nature is a strictly limited quantity. Man,
though acting on external characters alone, and often capriciously, can
produce within a short period a great result by adding up mere
individual differences in his domestic productions; and everyone admits
that species present individual differences. But, besides such
differences, all naturalists admit that natural varieties exist, which
are considered sufficiently distinct to be worthy of record in
systematic works.
No one has drawn any clear distinction between individual differences
and slight varieties, or between more plainly marked varieties and
sub-species and species. On separate continents, and on different parts
of the same continent when divided by barriers of any kind, what a
multitude of forms exist which some experienced naturalists rank as
varieties, others as geographical races or sub-species, and others as
distinct, though closely allied species!
If, then, animals and plants do vary, let it be ever so slightly or
slowly, why should not variations or individuals, differences which are
in any way beneficial, be preserved and accumulated through natural
selection, or the survival of the fittest? If man can, by patience,
select variations useful to him, why, under changing and complex
conditions of life, should not variations useful to Nature's living
products often arise, and be preserved, or selected? What limit can be
put to this power, acting during long ages and rigidly scrutinising the
whole constitution, structure, and habits of each creature--favouring
the good and rejecting the bad? I can see no limit to this power, in
slowly and beautifully adapting each form to the most complex relations
of life.
In the future I see open fields for far more important researches.
Psychology will be based on the foundation already well laid by Mr.
Herbert Spencer--that of the necessary acquirement of each mental power
and capacity by gradation. Much light will be thrown on the origin of
man and his history.
Authors of the highest eminence seem to be fully satisfied with the view
that each species has been independently created. To my mind it accords
better with what we know of the laws impressed on matter by the Creator
that the production and extinction of the past and present inhabitants
of the world should have been due to secondary causes, like those
determining the birth and death of the individual. When I view all
beings not as special creations, but as the lineal descendants of some
few beings which lived long before the first bed of the Cambrian system
was deposited, they seem to me to become ennobled. Judging from the
past, we may safely infer that not one living species will transmit its
unaltered likeness to a distant futurity.
Of the species now living very few will transmit progeny of any kind to
a far distant futurity; for the manner in which all organic beings are
grouped shows that the greater number of species in each genus, and all
the species in many genera, have left no descendants, but have become
utterly extinct. We can so far take a prophetic glance into futurity as
to foretell that it will be the common and widely-spread species,
belonging to the larger and dominant groups within each class, which
will ultimately prevail and procreate new and dominant species. As all
the living forms of life are the lineal descendants of those which lived
long before the Cambrian epoch, we may feel certain that the ordinary
succession by generation has never once been broken, and that no
cataclysm has desolated the whole world. We may look with some
confidence to a secure future of great length. As natural selection
works solely by and for the good of each being, all corporeal and mental
endowments will tend to progress towards perfection.
It is interesting to contemplate a tangled bank, clothed with many
plants of many kinds, with birds singing on the bushes, with various
insects flitting about, and with worms crawling through the damp earth,
and to reflect that these elaborately constructed forms, so different
from each other, and dependent upon each other in so complex a manner,
have all been produced by laws acting around us. These laws, taken in
the largest sense, being Growth with Reproduction; Inheritance, which is
almost implied by reproduction; Variability from the indirect and direct
action of the conditions of life, and from use and disuse; a ratio of
increase so high as to lead to a struggle for life, and, as a
consequence, to Natural Selection, entailing Divergence of Character
and the Extinction of less improved forms. Thus, from the war of Nature,
from famine and death, the most exalted object which we are capable of
conceiving, namely, the production of the higher animals, directly
follows. There is grandeur in this view of life, with its several
powers, having been originally breathed by the Creator into a few forms,
or into one; and that, whilst this planet has gone cycling on according
to the fixed law of gravity, from so simple a beginning endless forms
most beautiful and most wonderful have been, and are being, evolved.
SIR HUMPHRY DAVY
Elements of Chemical Philosophy
Humphry Davy, the celebrated natural philosopher, was born Dec. 17,
1778, at Penzance, England. At the age of seventeen he became an
apothecary's apprentice, and at the age of nineteen assistant at
Dr. Beddoes's pneumatic institution at Bristol. During researches
at the pneumatic institution he discovered the physiological
effects of "laughing gas," and made so considerable a reputation as
a chemist that at the age of twenty-two he was appointed lecturer,
and a year later professor, at the Royal Institution. For ten
years, from 1803, he was engaged in agricultural researches, and in
1813 published his "Elements of Agricultural Chemistry." During the
same decade he conducted important investigations into the nature
of chemical combination, and succeeded in isolating the elements
potassium, sodium, strontium, magnesium, and chlorine. In 1812 he
was knighted, and married Mrs. Apreece, _née_ Jane Kerr. In 1815 he
investigated the nature of fire-damp and invented the Davy safety
lamp. In 1818 he received a baronetcy, and two years later was
elected President of the Royal Society. On May 29, 1829, he died at
Geneva. Davy's "Elements of Chemical Philosophy," of which a
summary is given here, was published in one volume in 1812, being
the substance of lectures delivered before the Board of
Agriculture.
_I.--Forms and Changes of Matter_
The forms and appearances of the beings and substances of the external
world are almost infinitely various, and they are in a state of
continued alteration. In general, matter is found in four forms, as (1)
solids, (2) fluids, (3) gases, (4) ethereal substances.
1. _Solids._ Solids retain whatever mechanical form is given to them;
their parts are separated with difficulty, and cannot readily be made to
unite after separation. They may be either elastic or non-elastic, and
differ in hardness, in colour, in opacity, in density, in weight, and,
if crystalline, in crystalline form.
2. _Fluids._ Fluids, when in small masses, assume the spherical form;
their parts possess freedom of motion; they differ in density and
tenacity, in colour, and in opacity. They are usually regarded as
incompressible; at least, a very great mechanical force is required to
compress them.
3. _Gases._ Gases exist free in the atmosphere, but may be confined.
Their parts are highly movable; they are compressible and expansible,
and their volumes are inversely as the weight compressing them. All
known gases are transparent, and present only two or three varieties of
colour; they differ materially in density.
4. _Ethereal Substances._ Ethereal substances are known to us only in
their states of motion when acting upon our organs of sense, or upon
other matter, and are not susceptible of being confined. It cannot be
doubted that there is such matter in motion in space. Ethereal matter
differs either in its nature, or in its affections by motion, for it
produces different effects; for instance, radiant heat, and different
kinds of light.
All these forms of matter are under the influence of active forces, such
as gravitation, cohesion, heat, chemical and electrical attraction, and
these we must now consider.
1. _Gravitation._ When a stone is thrown into the atmosphere, it rapidly
descends towards the earth. This is owing to gravitation. All the great
bodies in the universe are urged towards each other by a similar force.
Bodies mutually gravitate towards each other, but the smaller body
proportionately more than the larger one; hence the power of gravity is
said to vary directly as the mass. Gravitation also varies with
distance, and acts inversely as the square of the distance.
2. _Cohesion._ Cohesion is the force which preserves the forms of
solids, and gives globularity to fluids. It is usually said to act only
at the surface of bodies or by their immediate contact; but this does
not seem to be the case. It certainly acts with much greater energy at
small distances, but the spherical form of minute portions of fluid
matter can be produced only by the attractions of all the parts of which
they are composed, for each other; and most of these attractions must be
exerted at sensible distances, so that gravitation and cohesion may be
mere modifications of the same general power of attraction.
3. _Heat._ When a body which occasions the sensation of heat on our
organs is brought into contact with another body which has no such
effect, the hot body contracts and loses to a certain extent its power
of communicating heat; and the other body expands. Different solids and
fluids expand very differently when heated, and the expansive power of
liquids, in general, is greater than that of solids.
It is evident that the density of bodies must be diminished by
expansion; and in the case of fluids and gases, the parts of which are
mobile, many important phenomena depend upon this circumstance. For
instance, if heat be applied to fluids and gases, the heated parts
change their places and rise, and the currents in the ocean and
atmosphere are due principally to this movement. There are very few
exceptions to the law of the expansion of bodies at the time they become
capable of communicating the sensation of heat, and these exceptions
seem to depend upon some chemical change in the constitution of bodies,
or on their crystalline arrangements.
The power which bodies possess of communicating or receiving heat is
known as _temperature_, and the temparature of a body is said to be high
or low with respect to another in proportion as it occasions an
expansion or contraction of its parts.
When equal volumes of different bodies of different temperatures are
suffered to remain in contact till they acquire the same temperature, it
is found that this temperature is not a mean one, as it would be in the
case of equal volumes of the same body. Thus if a pint of quicksilver
at 100° be mixed with a pint of water at 50°, the resulting temperature
is not 75°, but 70°; the mercury has lost thirty degrees, whereas the
water has only gained twenty degrees. This difference is said to depend
on the different _capacities_ of bodies for heat.
Not only do different bodies vary in their capacity for heat, but they
likewise acquire heat with very different degrees of celerity. This last
difference depends on the different power of bodies for _conducting_
heat, and it will be found that as a rule the densest bodies, with the
least capacity for heat, are the best conductors.
Heat, or the power of repulsion, may be considered as the _antagonist_
power to the attraction of cohesion. Thus solids by a certain increase
of temperature become fluids, and fluids gases; and, _vice versâ_, by a
diminution of temperature, gases become fluids, and fluids solids.
Proofs of the conversion of solids, fluids, or gases into ethereal
substances are not distinct. Heated bodies become luminous and give off
radiant heat, which affects the bodies at a distance, and it may
therefore be held that particles are thrown off from heated bodies with
great velocity, which, by acting on our organs, produce the sensations
of heat or light, and that their motion, communicated to the particles
of other bodies, has the power of expanding them. It may, however, be
said that the radiant matters emitted by bodies in ignition are specific
substances, and that common matter is not susceptible of assuming this
form; or it may be contended that the phenomena of radiation do in fact,
depend upon motions communicated to subtile matter everywhere existing
in space.
The temperatures at which bodies change their states from fluids to
solids, though in general definite, are influenced by a few
circumstances such as motion and pressure.
When solids are converted into fluids, or fluids into gases, there is
always a loss of heat of temperature; and, _vice versâ_, when gases are
converted into fluids, or fluids into solids, there is an increase of
heat of temperature, and in this case it is said that _latent_ heat is
absorbed or given out.
The expansion due to heat has been accounted for by supposing a subtile
fluid, or _caloric_, capable of combining with bodies and of separating
their parts from each other, and the absorption and liberation of latent
heat can be explained on this principle. But many other facts are
incompatible with the theory. For instance, metal may be kept hot for
any length of time by friction, so that if _caloric_ be pressed out it
must exist in an inexhaustible quantity. Delicate experiments have shown
that bodies, when heated, do not increase in weight.
It seems possible to account for all the phenomena of heat, if it be
supposed that in solids the particles are in a constant state of
vibratory motion, the particles of the hottest bodies moving with the
greatest velocity and through the greatest space; that in fluids and
gases the particles have not only vibratory motion, but also a motion
round their own axes with different velocities, and that in ethereal
substances the particles move round their own axes and separate from
each other, penetrating in right lines through space. Temperature may be
conceived to depend upon the velocity of the vibrations, increase of
capacity on the motion being performed in greater space; and the
diminution of temperature during the conversion of solids into fluids or
gases may be explained on the idea of the loss of vibratory motion in
consequence of the revolution of particles round their axes at the
moment when the body becomes fluid or aeriform, or from the loss of
rapidity of vibration in consequence of the motion of particles through
greater space.
4. _Chemical Attraction._ Oil and water will not _combine_; they are
said to have no chemical _attraction_ or _affinity_ for each other. But
if oil and solution of potassa in water be mixed, the oil and the
solution blend and form a soap; and they are said to attract each other
chemically or to have a _chemical affinity_ for each other. It is a
general character of chemical combination that it changes the qualities
of the bodies. Thus, corrosive and pungent substances may become mild
and tasteless; solids may become fluids, and solids and fluids gases.
No body will act chemically upon another body at any sensible distance;
apparent contact is necessary for chemical action. A freedom of motion
in the parts of the bodies or a want of cohesion greatly assists action,
and it was formerly believed that bodies cannot act chemically upon each
other unless one of them be fluid or gaseous.
Different bodies unite with different degrees of force, and hence one
body is capable of separating others from certain of their combinations,
and in consequence mutual decompositions of different compounds take
place. This has been called _double affinity_, or _complex chemical
affinity_.
As in all well-known compounds the proportions of the elements are in
certain definite ratios to each other, it is evident that these ratios
may be expressed by numbers; and if one number be employed to denote the
smallest quantity in which a body combines, all other quantities of the
same body will be multiples of this number, and the smallest proportions
into which the undecomposed bodies enter into union being known, the
constitution of the compounds they form may be learnt, and the element
which unites chemically in the smallest quantity being expressed by
unity, all the other elements may be represented by the relations of
their quantities to unity.
5. _Electrical Attraction._ A piece of dry silk briskly rubbed against a
warm plate of polished flint glass acquires the property of adhering to
the glass, and both the silk and the glass, if apart from each other,
attract light substances. The bodies are said to be _electrically
excited_. Probably, all bodies which differ from each other become
electrically excited when rubbed and pressed together. The electrical
excitement seems of two kinds. A pith-ball touched by glass excited by
silk repels a pith-ball touched by silk excited by metals. Electrical
excitement of the same nature as that in glass excited by silk is known
as _vitreous_ or _positive_, and electrical excitement of the opposite
nature is known as _resinous_ or _negative_.
A rod of glass touched by an electrified body is electrified only round
the point of contact. A rod of metal, on the contrary, suspended on a
rod of glass and brought into contact with an electrical surface,
instantly becomes electrical throughout. The glass is said to be a
_non-conductor_, or _insulating substance_; the metal a _conductor_.
When a non-conductor or imperfect conductor, provided it be a thin plate
of matter placed upon a conductor, is brought in contact with an excited
electrical body, the surface opposite to that of contact gains the
opposite electricity from that of the excited body, and if the plate be
removed it is found to possess two surfaces in opposite states. If a
conductor be brought into the neighbourhood of an excited body--the air,
which is a non-conductor, being between them--that extremity of the
conductor which is opposite to the excited body gains the opposite
electricity; and the other extremity, if opposite to a body connected
with the ground, gains the same electricity, and the middle point is not
electrical at all. This is known as _induced_ electricity.
The common exhibition of electrical effects is in attractions and
repulsions; but electricity also produces chemical phenomena. If a piece
of zinc and copper in contact with each other at one point be placed in
contact at other points with the same portion of water, the zinc will
corrode, and attract oxygen from the water much more rapidly than if it
had not been in contact with the copper; and if sulphuric acid be added,
globules of inflammable air are given off from the copper, though it is
not dissolved or acted upon.
Chemical phenomena in connection with electrical effects can be shown
even better by combinations in which the electrical effects are
increased by alterations of different metals and fluids--the so-called
_voltaic batteries_. Such are the decomposing powers of such batteries
that not even insoluble compounds are capable of resisting their energy,
for even glass, sulphate of baryta, fluorspar, etc., are slowly acted
upon, and the alkaline, earthy, or acid matter carried to the poles in
the common order.
The most powerful voltaic combinations are formed by substances that act
chemically with most energy upon each other, and such substances as
undergo no chemical changes in the combination exhibit no electrical
powers. Hence it was supposed that the electrical powers of metals were
entirely due to chemical changes; but this is not the case, for contact
produces electricity even when no chemical change can be observed.
_II.--Radiant or Ethereal Matter_
When similar thermometers are placed in different parts of the solar
beam, it is found that different effects are produced in the differently
coloured rays. The greatest heat is exhibited in the red rays, the least
in the violet rays; and in a space beyond the red rays, where there is
no visible light, the increase of temperature is greatest of all.
From these facts it is evident that matter set in motion by the sun has
the power of producing heat without light, and that its rays are less
refrangible than the visible rays. The invisible rays that produce heat
are capable of reflection as well as refraction in the same manner as
the visible rays.
Rays capable of producing heat with and without light proceed not only
from the sun, but also from bodies at the surface of the globe under
peculiar agencies or changes. If, for instance, a thermometer be held
near an ignited body, it receives an impression connected with an
elevation of temperature; this is partly produced by the conducting
powers of the air, and partly by an impulse which is instantaneously
communicated, even to a considerable distance. This effect is called the
radiation of terrestrial heat.
The manner in which the temperatures of bodies are affected by rays
producing heat is different for different substances, and is very much
connected with their colours. The bodies that absorb most light, and
reflect least, are most heated when exposed either to solar or
terrestrial rays. Black bodies are, in general, more heated than red;
red more than green; green more than yellow; and yellow more than white.
Metals are less heated than earthy or stony bodies, or than animal or
vegetable matters. Polished surfaces are less heated than rough
surfaces.
The bodies that have their temperatures most easily raised by heat rays
are likewise those that are most easily cooled by their own radiation,
or that at the same temperature emit most heat-making rays. Metals
radiate less heat than glass, glass less than vegetable substances, and
charcoal has the highest radiating powers of any body as yet made the
subject of experiment.
Radiant matter has the power of producing chemical changes partly
through its heating power, and partly through some other specific and
peculiar influence. Thus chlorine and hydrogen detonate when a mixture
of them is exposed to the solar beams, even though the heat is
inadequate to produce detonation.
If moistened silver be exposed to the different rays of the solar
spectrum, it will be found that no effect is produced upon it by the
least refrangible rays which occasion heat without light; that a slight
discoloration only will be produced by the red rays; that the effect of
blackening will be greater towards the violet end of the spectrum; and
that in a space beyond the violet, where there is no sensible heat or
light, the chemical effect will be very distinct. There seem to be rays,
therefore, more refrangible than the rays producing light and heat.
The general facts of the refraction and effects of the solar beam offer
an analogy to the agencies of electricity.
In general, in Nature the effects of the solar rays are very compounded.
Healthy vegetation depends upon the presence of the solar beams or of
light, and while the heat gives fluidity and mobility to the vegetable
juices, chemical effects are likewise occasioned, oxygen is separated
from them, and inflammable compounds are formed. Plants deprived of
light become white and contain an excess of saccharine and aqueous
particles; and flowers owe the variety of their hues to the influence of
the solar beams. Even animals require the presence of the rays of the
sun, and their colours seem to depend upon the chemical influence of
these rays.
Two hypotheses have been invented to account for the principal
operations of radiant matter. In the first it is supposed that the
universe contains a highly rare elastic substance, which, when put into
a state of undulation, produces those effects on our organs of sight
which constitute the sensations of vision and other phenomena caused by
solar and terrestrial rays. In the second it is conceived that particles
are emitted from luminous or heat-making bodies with great velocity, and
that they produce their effects by communicating their motions to
substances, or by entering into them and changing their composition.
Newton has attempted to explain the different refrangibility of the rays
of light by supposing them composed of particles differing in size. The
same great man has put the query whether light and common matter are not
convertible into each other; and, adopting the idea that the phenomena
of sensible heat depend upon vibrations of the particles of bodies,
supposes that a certain intensity of vibrations may send off particles
into free space, and that particles in rapid motion in right lines, in
losing their own motion, may communicate a vibratory motion to the
particles of terrestrial bodies.
MICHAEL FARADAY
Experimental Researches in Electricity
Michael Faraday was the son of a Yorkshire blacksmith, and was born
in London on September 22, 1791. At the age of twenty he became
assistant to Sir Humphry Davy, whose lectures he had attended at
the Royal Institution. Here he worked for the rest of his laborious
life, which closed on August 25, 1867. The fame of Faraday, among
those whose studies qualify them for a verdict, has risen steadily
since his death, great though it then was. His researches were of
truly epoch-making character, and he was the undisputed founder of
the modern science of electricity, which is rapidly coming to
dominate chemistry itself. Faraday excelled as a lecturer, and
could stand even the supreme test of lecturing to children.
Faraday's "Experimental Researches in Electricity" is a record of
some of the most brilliant experiments in the history of science.
In the course of his investigations he made discoveries which have
had momentous consequences. His discovery of the mutual relation of
magnets and of wires conducting electric currents was the beginning
of the modern dynamo and all that it involves; while his
discoveries of electric induction and of electrolysis were of equal
significance. Most of the researches are too technical for
epitomisation; but those given are representative of his manner and
methods.
_I.--Atmospheric Magnetism_
It is to me an impossible thing to perceive that two-ninths of the
atmosphere by weight is a highly magnetic body, subject to great changes
in its magnetic character, by variations in its temperature and
condensation or rarefaction, without being persuaded that it has much to
do with the variable disposition of the magnetic forces upon the surface
of the earth.
The earth is a spheroidal body consisting of paramagnetic and
diamagnetic substances irregularly disposed and intermingled; but for
the present the whole may be considered a mighty compound magnet. The
magnetic force of this great magnet is known to us only on the surface
of the earth and water of our planet, and the variations in the magnetic
lines of force which pass in or across this surface can be measured by
their action on small standard magnets; but these variations are limited
in their information, and do not tell us whether the cause is in the air
above or the earth beneath.
The lines of force issue from the earth in the northern and southern
parts and coalesce with each other over the equatorial, as would be the
case in a globe having one or two short magnets adjusted in relation to
its axis, and it is probable that the lines of force in their circuitous
course may extend through space to tens of thousands of miles. The lines
proceed through space with a certain degree of facility, but there may
be variations in space, _e.g._, variations in its temperature which
affect its power of transmitting the magnetic influence.
Between the earth and space, however, is interposed the atmosphere, and
at the bottom of the atmosphere we live. The atmosphere consists of four
volumes of nitrogen and one of oxygen uniformly mixed and acting
magnetically as a single medium. The _nitrogen_ of the air is, as
regards the magnetic force, neither paramagnetic nor diamagnetic,
whether dense or rare, or at high or low temperatures.
The _oxygen_ of the air, on the other hand, is highly paramagnetic,
being, bulk for bulk, equivalent to a solution of protosulphate of iron,
containing of the crystallised salt seventeen times the weight of the
oxygen. It becomes less paramagnetic, volume for volume, as it is
rarefied, and apparently in the simple proportion of its rarefaction,
the temperature remaining the same. When its temperature is raised--the
expansion consequent thereon being permitted--it loses very greatly its
paramagnetic force, and there is sufficient reason to conclude that when
its temperature is lowered its paramagnetic condition is exalted. These
characters oxygen preserves even when mingled with the nitrogen in the
air.
Hence the atmosphere is a highly magnetic medium, and this medium is
changed in its magnetic relations by every change in its density and
temperature, and must affect both the intensity and direction of the
magnetic force emanating from the earth, and may account for the
variations which we find in terrestrial magnetic power.
We may expect as the sun leaves us on the west some magnetic effect
correspondent to that of the approach of a body of cold air from the
east. Again, the innumerable circumstances that break up more or less
any average arrangement of the air temperatures may be expected to give
not merely differences in the regularity, direction, and degree of
magnetic variation, but, because of vicinity, differences so large as to
be many times greater than the mean difference for a given short period,
and they may also cause irregularities in the times of their occurrence.
Yet again, the atmosphere diminishes in density upwards, and this
diminution will affect the transmission of the electric force.
The result of the _annual variation_ that may be expected from the
magnetic constitution and condition of the atmosphere seems to me to be
of the following kind.
Since the axis of the earth's rotation is inclined 23° 28' to the plane
of the ecliptic, the two hemispheres will become alternately warmer and
cooler than each other. The air of the cooled hemisphere will conduct
magnetic influence more freely than if in the mean state, and the lines
of force passing through it will increase in amount, whilst in the other
hemisphere the warmed air will conduct with less readiness than before,
and the intensity will diminish. In addition to this effect of
temperature, there ought to be another due to the increase of the
ponderable portion of the air in the cooled hemisphere, consequent on
its contraction and the coincident expansion of the air in the warmer
half, both of which circumstances tend to increase the variation in
power of the two hemispheres from the normal state. Then, as the earth
rolls on its annual journey, that which was at one time the cooler
becomes the warmer hemisphere, and in its turn sinks as far below the
average magnetic intensity as it before had stood above it, while the
other hemisphere changes its magnetic condition from less to more
intense.
_II.--Electro-Chemical Action_
The theory of definite electrolytical or electro-chemical action appears
to me to touch immediately upon the absolute quantity of electricity
belonging to different bodies. As soon as we perceive that chemical
powers are definite for each body, and that the electricity which we can
loosen from each body has definite chemical action which can be
measured, we seem to have found the link which connects the proportion
of that we have evolved to the proportion belonging to the particles in
their natural state.
Now, it is wonderful to observe how small a quantity of a compound body
is decomposed by a certain quantity of electricity. One grain of water,
for instance, acidulated to facilitate conduction, will require an
electric current to be continued for three minutes and three-quarters to
effect its decomposition, and the current must be powerful enough to
keep a platina wire 1/104 inch in thickness red hot in the air during
the whole time, and to produce a very brilliant and constant star of
light if interrupted anywhere by charcoal points. It will not be too
much to say that this necessary quantity of electricity is equal to a
very powerful flash of lightning; and yet when it has performed its full
work of electrolysis, it has separated the elements of only a single
grain of water.
On the other hand, the relation between the conduction of the
electricity and the decomposition of the water is so close that one
cannot take place without the other. If the water be altered only in
that degree which consists in its having the solid instead of the fluid
state, the conduction is stopped and the decomposition is stopped with
it. Whether the conduction be considered as depending upon the
decomposition or not, still the relation of the two functions is equally
intimate.
Considering this close and twofold relation--namely, that without
decomposition transmission of electricity does not occur, and that for a
given definite quantity of electricity passed an equally definite and
constant quantity of water or other matter is decomposed; considering
also that the agent, which is electricity, is simply employed in
overcoming electrical powers in the body subjected to its action, it
seems a probable and almost a natural consequence that the quantity
which passes is the equivalent of that of the particles separated;
_i.e._, that if the electrical power which holds the elements of a grain
of water in combination, or which makes a grain of oxygen and hydrogen
in the right proportions unite into water when they are made to combine,
could be thrown into a current, it would exactly equal the current
required for the separation of that grain of water into its elements
again; in other words, that the electricity which decomposes and that
which is evolved by the decomposition of a certain quantity of matter
are alike.
This view of the subject gives an almost overwhelming idea of the
extraordinary quantity or degree of electric power which naturally
belongs to the particles of matter, and the idea may be illustrated by
reference to the voltaic pile.
The source of the electricity in the voltaic instrument is due almost
entirely to chemical action. Substances interposed between its metals
are all electrolytes, and the current cannot be transmitted without
their decomposition. If, now, a voltaic trough have its extremities
connected by a body capable of being decomposed, such as water, we shall
have a continuous current through the apparatus, and we may regard the
part where the acid is acting on the plates and the part where the
current is acting upon the water as the reciprocals of each other. In
both parts we have the two conditions, _inseparable in such bodies as
these_: the passing of a current, and decomposition. In the one case we
have decomposition associated with a current; in the other, a current
followed by decomposition.
Let us apply this in support of my surmise respecting the enormous
electric power of each particle or atom of matter.
Two wires, one of platina, and one of zinc, each one-eighteenth of an
inch in diameter, placed five-sixteenths of an inch apart, and immersed
to the depth of five-eighths of an inch in acid, consisting of one drop
of oil of vitriol and four ounces of distilled water at a temperature of
about 60° Fahrenheit, and connected at the other ends by a copper wire
eighteen feet long, and one-eighteenth of an inch in thickness, yielded
as much electricity in little more than three seconds of time as a
Leyden battery charged by thirty turns of a very large and powerful
plate electric machine in full action. This quantity, although
sufficient if passed at once through the head of a rat or cat to have
killed it, as by a flash of lightning, was evolved by the mutual action
of so small a portion of the zinc wire and water in contact with it that
the loss of weight by either would be inappreciable; and as to the water
which could be decomposed by that current, it must have been insensible
in quantity, for no trace of hydrogen appeared upon the surface of the
platina during these three seconds. It would appear that 800,000 such
charges of the Leyden battery would be necessary to decompose a single
grain of water; or, if I am right, to equal the quantity of electricity
which is naturally associated with the elements of that grain of water,
endowing them with their mutual chemical affinity.
This theory of the definite evolution and the equivalent definite action
of electricity beautifully harmonises the associated theories of
definite proportions and electro-chemical affinity.
According to it, the equivalent weights of bodies are simply those
quantities of them which contain equal quantities of electricity, or
have naturally equal electric powers, it being the electricity which
_determines_ the equivalent number, _because_ it determines the
combining force. Or, if we adopt the atomic theory or phraseology, then
the atoms of bodies which are equivalent to each other in their ordinary
chemical action have equal quantities of electricity naturally
associated with them. I cannot refrain from recalling here the beautiful
idea put forth, I believe, by Berzelius in his development of his views
of the electro-chemical theory of affinity, that the heat and light
evolved during cases of powerful combination are the consequence of the
electric discharge which is at the moment taking place. The idea is in
perfect accordance with the view I have taken of the quantity of
electricity associated with the particles of matter.
The definite production of electricity in association with its definite
action proves, I think, that the current of electricity in the voltaic
pile is sustained by chemical decomposition, or, rather, by chemical
action, and not by contact only. But here, as elsewhere, I beg to
reserve my opinion as to the real action of contact.
Admitting, however, that chemical action is the source of electricity,
what an infinitely small fraction of that which is active do we obtain
and employ in our voltaic batteries! Zinc and platina wires
one-eighteenth of an inch in diameter and about half an inch long,
dipped into dilute sulphuric acid, so weak that it is not sensibly sour
to the tongue, or scarcely sensitive to our most delicate test papers,
will evolve more electricity in one-twentieth of a minute than any man
would willingly allow to pass through his body at once.
The chemical energy represented by the satisfaction of the chemical
affinities of a grain of water and four grains of zinc can evolve
electricity equal in quantity to that of a powerful thunderstorm. Nor is
it merely true that the quantity is active; it can be directed--made to
perform its full equivalent duty. Is there not, then, great reason to
believe that, by a closer investigation of the development and action of
this subtile agent, we shall be able to increase the power of our
batteries, or to invent new instruments which shall a thousandfold
surpass in energy those we at present possess?
_III.--The Gymnotus, or Electric Eel_
Wonderful as are the laws and phenomena of electricity when made evident
to us in inorganic or dead matter, their interest can bear scarcely any
comparison with that which attaches to the same force when connected
with the nervous system and with life.
The existence of animals able to give the same concussion to the living
system as the electrical machine, the voltaic battery, and the
thunderstorm being made known to us by various naturalists, it became
important to identify their electricity with the electricity produced by
man from dead matter. In the case of the _Torpedo_ [a fish belonging to
the family of Electric Rings] this identity has been fully proved, but
in the case of the _Gymnotus_ the proof has not been quite complete, and
I thought it well to obtain a specimen of the latter fish.
A gymnotus being obtained, I conducted a series of experiments. Besides
the hands two kinds of collectors of electricity were used--one with a
copper disc for contact with the fish, and the other with a plate of
copper bent into saddle shape, so that it might enclose a certain
extent of the back and sides of the fish. These conductors, being put
over the fish, collected power sufficient to produce many electric
effects.
SHOCK. The shock was very powerful when the hands were placed one near
the head and the other near the tail, and the nearer the hands were
together, within certain limits, the less powerful was the shock. The
disc conductors conveyed the shock very well when the hands were wetted.
GALVANOMETER. A galvanometer was readily affected by using the saddle
conductors, applied to the anterior and posterior parts of the gymnotus.
A powerful discharge of the fish caused a deflection of thirty or forty
degrees. The deflection was constantly in a given direction, the
electric current being always from the anterior part of the animal
through the galvanometer wire to the posterior parts. The former were,
therefore, for the time externally positive and the latter negative.
MAKING A MAGNET. When a little helix containing twenty-two feet of
silked wire wound on a quill was put into a circuit, and an annealed
steel needle placed in the helix, the needle became a magnet; and the
direction of its polarity in every cast indicated a current from the
anterior to the posterior parts of the gymnotus.
CHEMICAL DECOMPOSITION. Polar decomposition of a solution of iodide of
potassium was easily obtained.
EVOLUTION OF HEAT. Using a Harris' thermo-electrometer, we thought we
were able, in one instance, to observe a feeble elevation of
temperature.
SPARK. By suitable apparatus a spark was obtained four times.
Such were the general electric phenomena obtained from the gymnotus, and
on several occasions many of the phenomena were obtained together. Thus,
a magnet was made, a galvanometer deflected, and, perhaps, a wire heated
by one single discharge of the electric force of the animal. When the
shock is strong, it is like that of a large Leyden battery charged to a
low degree, or that of a good voltaic battery of, perhaps, one hundred
or more pairs of plates, of which the circuit is completed for a moment
only.
I endeavoured by experiment to form some idea of the quantity of
electricity, and came to the conclusion that a single medium discharge
of the fish is at least equal to the electricity of a Leyden battery of
fifteen jars, containing 3,500 square inches of glass coated on both
sides, charged to its highest degree. This conclusion is in perfect
accordance with the degree of deflection which the discharge can produce
in a galvanometer needle, and also with the amount of chemical
decomposition produced in the electrolysing experiments.
The gymnotus frequently gives a double and even a triple shock, with
scarcely a sensible interval between each discharge.
As at the moment of shock the anterior parts are positive and the
posterior negative, it may be concluded that there is a current from the
former to the latter through every part of the water which surrounds the
animal, to a considerable distance from its body. The shock which is
felt, therefore, when the hands are in the most favourable position is
the effect of a very small portion only of the electricity which the
animal discharges at the moment, by far the largest portion passing
through the surrounding water.
This enormous external current must be accompanied by some effect within
the fish _equivalent_ to a current, the direction of which is from the
tail towards the head, and equal to the sum of _all these external_
forces. Whether the process of evolving or exciting the electricity
within the fish includes the production of the internal current, which
is not necessarily so quick and momentary as the external one, we cannot
at present say; but at the time of the shock the animal does not
apparently feel the electric sensation which he causes in those around
him.
The gymnotus can stun and kill fish which are in very various relations
to its own body. The extent of surface which the fish that is about to
be struck offers to the water conducting the electricity increases the
effect of the shock, and the larger the fish, accordingly, the greater
must be the shock to which it will be subjected.
The Chemical History of a Candle
"The Chemical History of a Candle" was the most famous course in
the long and remarkable series of Christmas lectures, "adapted to a
juvenile auditory," at the Royal Institution, and remains a
rarely-approached model of what such lectures should be. They were
illustrated by experiments and specimens, but did not depend upon
these for coherence and interest. They were delivered in 1860-61,
and have just been translated, though all but half-a-century old,
into German.
_I.--Candles and their Flames_
There is not a law under which any part of this universe is governed
that does not come into play in the phenomena of the chemical history of
a candle. There is no better door by which you can enter into the study
of natural philosophy than by considering the physical phenomena of a
candle.
And now, my boys and girls, I must first tell you of what candles are
made. Some are great curiosities. I have here some bits of timber,
branches of trees particularly famous for their burning. And here you
see a piece of that very curious substance taken out of some of the bogs
in Ireland, called _candle-wood_--a hard, strong, excellent wood,
evidently fitted for good work as a resister of force, and yet withal
burning so well that, where it is found, they make splinters of it, and
torches, since it burns like a candle, and gives a very good light
indeed. And in this wood we have one of the most beautiful illustrations
of the general nature of a candle that I can possibly give. The fuel
provided, the means of bringing that fuel to the place of chemical
action, the regular and gradual supply of air to that place of
action--heat and light all produced by a little piece of wood of this
kind, forming, in fact, a natural candle.
But we must speak of candles as they are in commerce. Here are a couple
of candles commonly called dips. They are made of lengths of cotton cut
off, hung up by a loop, dipped into melted tallow, taken out again and
cooled; then re-dipped until there is an accumulation of tallow round
the cotton. However, a candle, you know, is not now a greasy thing like
an ordinary tallow candle, but a clean thing; and you may almost scrape
off and pulverise the drops which fall from it without soiling anything.
The candle I have in my hand is a stearine candle, made of stearine from
tallow. Then here is a sperm candle, which comes from the purified oil
of the spermaceti whale. Here, also, are yellow beeswax and refined
beeswax from which candles are made. Here, too, is that curious
substance called paraffin, and some paraffin candles made of paraffin
obtained from the bogs of Ireland. I have here also a substance brought
from Japan, a sort of wax which a kind friend has sent me, and which
forms a new material for the manufacture of candles.
Now, as to the light of the candle. We will light one or two, and set
them at work in the performance of their proper function. You observe a
candle is a very different thing from a lamp. With a lamp you take a
little oil, fill your vessel, put in a little moss, or some cotton
prepared by artificial means, and then light the top of the wick. When
the flame runs down the cotton to the oil, it gets stopped, but it goes
on burning in the part above. Now, I have no doubt you will ask, how is
it that the oil, which will not burn of itself, gets up to the top of
the cotton, where it will burn? We shall presently examine that; but
there is a much more wonderful thing about the burning of a candle than
this. You have here a solid substance with no vessel to contain it; and
how is it that this solid substance can get up to the place where the
flame is? Or, when it is made a fluid, then how is it that it keeps
together? This is a wonderful thing about a candle.
You see, then, in the first instance, that a beautiful cup is formed. As
the air comes to the candle, it moves upwards by the force of the
current which the heat of the candle produces, and it so cools all the
sides of the wax, tallow, or fuel as to keep the edge much cooler than
the part within; the part within melts by the flame that runs down the
wick as far as it can go before it is stopped, but the part on the
outside does not melt. If I made a current in one direction, my cup
would be lopsided, and the fluid would consequently run over--for the
same force of gravity which holds worlds together, holds this fluid in a
horizontal position. You see, therefore, that the cup is formed by this
beautifully regular ascending current of air playing upon all sides,
which keeps the exterior of the candle cool. No fuel would serve for a
candle which has not the property of giving this cup, except such fuel
as the Irish bogwood, where the material itself is like a sponge, and
holds its own fuel.
You see now why you have such a bad result if you burn those beautiful
fluted candles, which are irregular, intermittent in their shape, and
cannot therefore have that nicely-formed edge to the cup which is the
great beauty in a candle. I hope you will now see that the perfection of
a process--that is, its utility--is the better point of beauty about it.
It is not the best-looking thing, but the best-acting thing which is the
most advantageous to us. This good-looking candle is a bad burning one.
There will be a guttering round about it because of the irregularity of
the stream of air and the badness of the cup which is formed thereby.
You may see some pretty examples of the action of the ascending current
when you have a little gutter run down the side of a candle, making it
thicker there than it is elsewhere. As the candle goes on burning, that
keeps its place and forms a little pillar sticking up by the side,
because, as it rises higher above the rest of the wax or fuel, the air
gets better round it, and it is more cooled and better able to resist
the action of the heat at a little distance. Now, the greatest mistakes
and faults with regard to candles, as in many other things, often bring
with them instruction which we should not receive if they had not
occurred. You will always remember that whenever a result happens,
especially if it be new, you should say: "What is the cause? Why does it
occur?" And you will in the course of time find out the reason.
Then there is another point about these candles which will answer a
question--that is, as to the way in which this fluid gets out of the
cup, up to the wick, and into the place of combustion. You know that the
flames on these burning wicks in candles made of beeswax, stearine, or
spermaceti, do not run down to the wax or other matter, and melt it all
away, but keep to their own right place. They are fenced off from the
fluid below, and do not encroach on the cup at the sides.
I cannot imagine a more beautiful example than the condition of
adjustment under which a candle makes one part subserve to the other to
the very end of its action. A combustible thing like that, burning away
gradually, never being intruded upon by the flame, is a very beautiful
sight; especially when you come to learn what a vigorous thing flame is,
what power it has of destroying the wax itself when it gets hold of it,
and of disturbing its proper form if it come only too near.
But how does the flame get hold of the fuel? There is a beautiful point
about that. It is by what is called capillary attraction that the fuel
is conveyed to the part where combustion goes on, and is deposited
there, not in a careless way, but very beautifully in the very midst of
the centre of action which takes place around it.
_II.--The Brightness of the Candle_
Air is absolutely necessary for combustion; and, what is more, I must
have you understand that _fresh_ air is necessary, or else we should be
imperfect in our reasoning and our experiments. Here is a jar of air. I
place it over a candle, and it burns very nicely in it at first, showing
that what I have said about it is true; but there will soon be a change.
See how the flame is drawing upwards, presently fading, and at last
going out. And going out, why? Not because it wants air merely, for the
jar is as full now as it was before, but it wants pure, fresh air. The
jar is full of air, partly changed, partly not changed; but it does not
contain sufficient of the fresh air for combustion.
Suppose I take a candle, and examine that part of it which appears
brightest to our eyes. Why, there I get these black particles, which are
just the smoke of the candle; and this brings to mind that old
employment which Dean Swift recommended to servants for their amusement,
namely, writing on the ceiling of a room with a candle. But what is that
black substance? Why, it is the same carbon which exists in the candle.
It evidently existed in the candle, or else we should not have had it
here. You would hardly think that all those substances which fly about
London in the form of soots and blacks are the very beauty and life of
the flame. Here is a piece of wire gauze which will not let the flame go
through it, and I think you will see, almost immediately, that, when I
bring it low enough to touch that part of the flame which is otherwise
so bright, it quells and quenches it at once, and allows a volume of
smoke to rise up.
Whenever a substance burns without assuming the vaporous state--whether
it becomes liquid or remains solid--it becomes exceedingly luminous.
What I say is applicable to all substances--whether they burn or whether
they do not burn--that they are exceedingly bright if they retain their
solid state when heated, and that it is to this presence of solid
particles in the candle-flame that it owes its brilliancy.
I have here a piece of carbon, or charcoal, which will burn and give us
light exactly in the same manner as if it were burnt as part of a
candle. The heat that is in the flame of a candle decomposes the vapour
of the wax, and sets free the carbon particles--they rise up heated and
glowing as this now glows, and then enter into the air. But the
particles when burnt never pass off from a candle in the form of carbon.
They go off into the air as a perfectly invisible substance, about which
we shall know hereafter.
Is it not beautiful to think that such a process is going on, and that
such a dirty thing as charcoal can become so incandescent? You see, it
comes to this--that all bright flames contain these solid particles; all
things that burn and produce solid particles, either during the time
they are burning, as in the candle, or immediately after being burnt, as
in the case of the gunpowder and iron-filings--all these things give us
this glorious and beautiful light.
_III.--The Products of Combustion_
We observe that there are certain products as the result of the
combustion of a candle, and that of these products one portion may be
considered as charcoal, or soot; that charcoal, when afterwards burnt,
produces some other product--carbonic acid, as we shall see; and it
concerns us very much now to ascertain what yet a third product is.
Suppose I take a candle and place it under a jar. You see that the sides
of the jar become cloudy, and the light begins to burn feebly. It is the
products, you see, which make the light so dim, and this is the same
thing which makes the sides of the jar so opaque. If you go home and
take a spoon that has been in the cold air, and hold it over a
candle--not so as to soot it--you will find that it becomes dim, just as
that jar is dim. If you can get a silver dish, or something of that
kind, you will make the experiment still better. It is _water_ which
causes the dimness, and we can make it, without difficulty, assume the
form of a liquid.
And so we can go on with almost all combustible substances, and we find
that if they burn with a flame, as a candle, they produce water. You may
make these experiments yourselves. The head of a poker is a very good
thing to try with, and if it remains cold long enough over the candle,
you may get water condensed in drops on it; or a spoon, or a ladle, or
anything else may be used, provided it be clean, and can carry off the
heat, and so condense the water.
And now--to go into the history of this wonderful production of water
from combustibles, and by combustion--I must first of all tell you that
this water may exist in different conditions; and although you may now
be acquainted with all its forms, they still require us to give a little
attention to them for the present, so that we may perceive how the
water, whilst it goes through its protean changes, is entirely and
absolutely the same thing, whether it is produced from a candle, by
combustion, or from the rivers or ocean.
First of all, water, when at the coldest, is ice. Now, we speak of water
as water; whether it be in its solid, or liquid, or gaseous state, we
speak of it chemically as water.
We shall not in future be deceived, therefore, by any changes that are
produced in water. Water is the same everywhere, whether produced from
the ocean or from the flame of the candle. Where, then, is this water
which we get from a candle? It evidently comes, as to part of it, from
the candle; but is it within the candle beforehand? No! It is not in the
candle; and it is not in the air round about the candle, which is
necessary for its combustion. It is neither in one nor the other, but it
comes from their conjoint action, a part from the candle, a part from
the air. And this we have now to trace.
If we decompose water we can obtain from it a gas. This is hydrogen--a
body classed amongst those things in chemistry which we call elements,
because we can get nothing else out of them. A candle is not an
elementary body, because we can get carbon out of it; we can get this
hydrogen out of it, or at least out of the water which it supplies. And
this gas has been so named hydrogen because it is that element which, in
association with another, generates water.
Hydrogen gives rise to no substance that can become solid, either during
combustion or afterwards, as a product of its combustion. But when it
burns it produces water only; and if we take a cold glass and put it
over the flame, it becomes damp, and you have water produced immediately
in appreciable quantity, and nothing is produced by its combustion but
the same water which you have seen the flame of a candle produce. This
hydrogen is the only thing in Nature that furnishes water as the sole
product of combustion.
Water can be decomposed by electricity, and then we find that its other
constituent is the gas oxygen in which, as can easily be shown, a candle
or a lamp burns much more brilliantly than it does in air, but produces
the same products as when it burns in air. We thus find that oxygen is
a constituent of the air, and by burning something in the air we can
remove the oxygen therefrom, leaving behind for our study the nitrogen,
which constitutes about four-fifths of the air, the oxygen accounting
for nearly all the rest.
The other great product of the burning of a candle is carbonic acid--a
gas formed by the union of the carbon of the candle and the oxygen of
the air. Whenever carbon burns, whether in a candle or in a living
creature, it produces carbonic acid.
_IV.--Combustion and Respiration_
Now I must take you to a very interesting part of our subject--to the
relation between the combustion of a candle and that living kind of
combustion which goes on within us. In every one of us there is a living
process of combustion going on very similar to that of a candle. For it
is not merely true in a poetical sense--the relation of the life of man
to a taper. A candle will burn some four, five, six, or seven hours.
What, then, must be the daily amount of carbon going up into the air in
the way of carbonic acid? What a quantity of carbon must go from each of
us in respiration! A man in twenty-four hours converts as much as seven
ounces of carbon into carbonic acid; a milch cow will convert seventy
ounces, and a horse seventy-nine ounces, solely by the act of
respiration. That is, the horse in twenty-four hours burns seventy-nine
ounces of charcoal, or carbon, in his organs of respiration to supply
his natural warmth in that time.
All the warm-blooded animals get their warmth in this way, by the
conversion of carbon; not in a free state, but in a state of
combination. And what an extraordinary notion this gives us of the
alterations going out in our atmosphere! As much as 5,000,000 pounds of
carbonic acid is formed by respiration in London alone in twenty-four
hours. And where does all this go? Up into the air. If the carbon had
been like lead or iron, which, in burning, produces a solid substance,
what would happen? Combustion would not go on. As charcoal burns, it
becomes a vapour and passes off into the atmosphere, which is the great
vehicle, the great carrier, for conveying it away to other places. Then,
what becomes of it?
Wonderful is it to find that the change produced by respiration, which
seems so injurious to us, for we cannot breathe air twice over, is the
very life and support of plants and vegetables that grow upon the
surface of the earth. It is the same also under the surface in the great
bodies of water, for fishes and other animals respire upon the same
principle, though not exactly by contact with the open air. They respire
by the oxygen which is dissolved from the air by the water, and form
carbonic acid; and they all move about to produce the one great work of
making the animal and vegetable kingdoms subservient to each other.
All the plants growing upon the surface of the earth absorb carbon.
These leaves are taking up their carbon from the atmosphere, to which we
have given it in the form of carbonic acid, and they are prospering.
Give them a pure air like ours, and they could not live in it; give them
carbon with other matters, and they live and rejoice. So are we made
dependent not merely upon our fellow-creatures, but upon our
fellow-existers, all Nature being tied by the laws that make one part
conduce to the good of the other.
AUGUSTE FOREL
The Senses of Insects
Auguste Forel, who in 1909 retired from the Chair of Morbid
Psychology in the University of Zürich, was born on September 1,
1848, and is one of the greatest students of the minds and senses
of the lower animals and mankind. Among his most famous works are
his "Hygiene of Nerves and Mind," his great treatise on the whole
problem of sex in human life, of which a cheap edition entitled
"Sexual Ethics" is published, his work on hypnotism, and his
numerous contributions to the psychology of insects. The chief
studies of this remarkable and illustrious student and thinker for
many decades past have been those of the senses and mental
faculties of insects. He has recorded the fact that his study of
the beehive led him to his present views as to the right
constitution of the state--views which may be described as
socialism with a difference. His work on insects has served the
study of human psychology, and is in itself the most important
contribution to insect psychology ever made by a single student.
Only within the last two years has the work of Forel, long famous
on the European Continent, begun to be known abroad.
_I.--Insect Activity and Instinct_
This subject is one of great interest, as much from the standpoint of
biology as from that of comparative psychology. The very peculiar
mechanism of instincts always has its starting-point in sensations. To
comprehend this mechanism it is essential to understand thoroughly the
organs of sense and their special functions.
It is further necessary to study the co-ordination which exists between
the action of the different senses, and leads to their intimate
connection with the functions of the nerve-centres, that is to say, with
the specially instinctive intelligence of insects. The whole question
is, therefore, a chapter of comparative psychology, a chapter in which
it is necessary to take careful note of every factor, to place oneself,
so to speak, on a level with the mind of an insect, and, above all, to
avoid the anthropomorphic errors with which works upon the subject are
filled.
At the same time the other extreme must equally be
avoided--"anthropophobia," which at all costs desires to see in every
living organism a "machine," forgetting that a "machine" which lives,
that is to say, which grows, takes in nutriment, and strikes a balance
between income and expenditure, which, in a word, continually
reconstructs itself, is not a "machine," but something entirely
different. In other words, it is necessary to steer clear of two
dangers. We must avoid (1) identifying the mind of an insect with our
own, but, above all, (2) imagining that we, with what knowledge we
possess, can reconstruct the mind by our chemical and physical laws.
On the other hand, we have to recognise the fact that this mind, and the
sensory functions which put it on its guard, are derived, just as with
our human selves, from the primitive protoplasmic life. This life, so
far as it is specialised in the nervous system by nerve irritability and
its connections with the muscular system, is manifested under two
aspects. These may be likened to two branches of one trunk.
(_a_) _Automatic_ or _instinctive_ activity. This, though perfected by
repetition, is definitely inherited. It is uncontrollable and constant
in effect, adapted to the circumstances of the special life of the race
in question. It is this curious instinctive adaptation--which is so
intelligent when it carries out its proper task, so stupid and incapable
when diverted to some other purpose--that has deceived so many
scientists and philosophers by its insidious analogy with humanly
constructed machines.
But, automatic as it may appear, instinct is not invariable. In the
first place, it presents a racial evolution which of itself alone
already demonstrates a certain degree of plasticity from generation to
generation. It presents, further, individual variations which are more
distinct as it is less deeply fixed by heredity. Thus the divergent
instincts of two varieties, _e.g._, of insects, present more individual
variability and adaptability than do those instincts common to all
species of a genus. In short, if we carefully study the behaviour of
each individual of a species of insects with a developed brain (as has
been done by P. Huber, Lubbock, Wasmann, and myself, among others, for
bees, wasps, and ants), we are not long in finding noteworthy
differences, especially when we put the instinct under abnormal
conditions. We then force the nervous activity of these insects to
present a second and plastic aspect, which to a large extent has been
hidden from us under their enormously developed instinct.
(_b_) The _plastic_ or _adaptive_ activity is by no means, as has been
so often suggested, a derivative of instinct. It is primitive. It is
even the fundamental condition of the evolution of life. The living
being is distinguished by its power of adaptation; even the amoeba is
plastic. But in order that one individual may adapt itself to a host of
conditions and possibilities, as is the case with the higher mammals and
especially with man, the brain requires an enormous quantity of nerve
elements. But this is not the case with the fixed and specialised
adaptation of instinct.
In secondary automatism, or habit, which we observe in ourselves, it is
easy to study how this activity, derived from plastic activity, and ever
becoming more prompt, complex, and sure (technical habits), necessitates
less and less expenditure of nerve effort. It is very difficult to
understand how inherited instinct, hereditary automatism, could have
originated from the plastic activities of our ancestors. It seems as if
a very slow selection, among individuals best adapted in consequence of
fortunate parentage, might perhaps account for it.
To sum up, every animal possesses two kinds of activity in varying
degrees, sometimes one, sometimes the other predominating. In the lowest
beings they are both rudimentary. In insects, special automatic activity
reaches the summit of development and predominance; in man, on the
contrary, with his great brain development, plastic activity is elevated
to an extraordinary height, above all by language, and before all by
written language, which substitutes graphic fixation for secondary
automatism, and allows the accumulation outside the brain of the
knowledge of past generations, thus serving his plastic activity, at
once the adapter and combiner of what the past has bequeathed to it.
According to the families, _genera_, and species of insects, the
development of different senses varies extremely. We meet with most
striking contrasts, and contrasts which have not been sufficiently
noticed. Certain insects, dragon-flies, for instance, live almost
entirely by means of sight. Others are blind, or almost blind, and
subsist exclusively by smell and taste (insects inhabiting caves, most
working ants). Hearing is well developed in certain forms (crickets,
locusts), but most insects appear not to hear, or to hear with
difficulty. Despite their thick, chitinous skeleton, almost all insects
have extremely sensitive touch, especially in the antennæ, but not
confined thereto.
It is absolutely necessary to bear in mind the mental faculties of
insects in order to judge with a fair degree of accuracy how they use
their senses. We shall return to that point when summing up.
_II.--The Vision of Insects_
In vision we are dealing with a certain definite stimulus--light, with
its two modifications, colour and motion. Insects have two sets of
organs for vision, the faceted eye and the so-called simple eye, or
ocellus. These have been historically derived from one and the same
organ. In order to exercise the function of sight the facets need a
greater pencil of light rays by night than by day. To obtain the same
result we dilate the pupil. But nocturnal insects are dazzled by the
light of day, and diurnal insects cannot see by night, for neither
possess the faculty of accommodation. Insects are specially able to
perceive motion, but there are only very few insects that can see
distinctly.
For example, I watched one day a wasp chasing a fly on the wall of a
veranda, as is the habit of this insect at the end of summer and in the
autumn. She dashed violently in flight at the flies sitting on the wall,
which mostly escaped. She continued her pursuit with remarkable
pertinacity, and succeeded on several occasions in catching a fly, which
she killed, mutilated, and bore away to her nest. Each time she quickly
returned to continue the hunt.
In one spot of the wall was stuck a black nail, which was just the size
of a fly, and I saw the wasp very frequently deceived by this nail, upon
which she sprang, leaving it as soon as she perceived her error on
touching it. Nevertheless, she made the same mistake with the nail
shortly after. I have often made similar observations. We may certainly
conclude that the wasp saw something of the size of a fly, but without
distinguishing the details; therefore she saw it indistinctly. Evidently
a wasp does not only perceive motion; she also distinguishes the size of
objects. When I put dead flies on a table to be carried off by another
wasp, she took them, one after another, as well as spiders and other
insects of but little different size placed by their side. On the other
hand, she took no notice of insects much larger or much smaller put
among the flies.
Most entomologists have observed with what ingenuity and sureness
dragon-flies distinguish, follow, and catch the smallest insects on the
wing. Of all insects, they have the best sight. Their enormous convex
eyes have the greatest number of facets. Their number has been estimated
at 12,000, and even at 17,000. Their aerial chases resemble those of the
swallows. By trying to catch them at the edge of a large pond, one can
easily convince oneself that the dragon-flies amuse themselves by making
sport of the hunter; they will always allow one to approach just near
enough to miss catching them. It can be seen to what degree they are
able to measure the distance and reach of their enemy.
It is an absolute fact that dragon-flies, unless it is cold or in the
evening, always manage to fly at just that distance at which the student
cannot touch them; and they see perfectly well whether one is armed with
a net or has nothing but his hands; one might even say that they measure
the length of the handle of the net, for the possession of a long handle
is no advantage. They fly just out of reach of one's instrument,
whatever trouble one may give oneself by hiding it from them and
suddenly lunging as they fly off. Whoever watches butterflies and flies
will soon see that these insects also can measure the distance of such
objects as are not far from them. The males and females of bees and ants
distinguish one another on the wing. It is rare for an individual to
lose sight of the swarm or to miss what it pursues flying. It has been
proved that the sense of smell has nothing to do with this matter. Thus
insects, though without any power of accommodation for light or
distance, are able to perceive objects at different distances.
It is known that many insects will blindly fly and dash against a lamp
at night, until they burn themselves. It has often been wrongly thought
that they are fascinated. We ought first to remember that natural
lights, concentrated at one point like our artificial lights, are
extremely rare in Nature. The light of day, which is the light of wild
animals, is not concentrated at one point. Insects, when they are in
darkness--underground, beneath bark or leaves--are accustomed to reach
the open air, where the light is everywhere diffused, by directing
themselves towards the luminous point. At night, when they fly towards a
lamp, they are evidently deceived, and their small brains cannot
comprehend the novelty of this light concentrated at one spot.
Consequently, their fruitless efforts are again and again renewed
against the flame, and the poor innocents end by burning themselves.
Several domestic insects, which have become little by little adapted to
artificial light in the course of generations, no longer allow
themselves to be deceived thereby. This is the case with house-flies.
Bees distinguish all colours, and seldom confound any but blue and
green; while wasps scarcely react to differences of colour, but note
better the shape of an object, and note, for instance, where the place
of honey is; so that a change of colour on the disc whereon the honey is
placed hardly upsets them. Further, wasps have a better sense of smell
than bees.
The chief discovery regarding the vision of insects made in the last
thirty years is that of Lubbock, who proved that ants perceive the
ultra-violet rays of the spectrum, which we are unable, or almost
unable, to perceive.
It has lately been proved also that many insects appreciate light by the
skin.
They do not see as clearly as we do; but when they possess
well-developed compound eyes they appreciate size, and more or less
distinctly the contours of objects.
Ants have a great faculty for recognition, which probably testifies to
their vision and visual memory. Lubbock observed ants which actually
recognised each other after more than a year of separation.
_III.--Smell, Taste, Hearing, Pain_
Smell is very important in insects. It is difficult for us to judge of,
since man is of all the vertebrates except the whales, perhaps, the one
in which this sense is most rudimentary. We can evidently, therefore,
form only a feeble idea of the world of knowledge imparted by a smell to
a dog, a mole, a hedgehog, or an insect. The instruments of smell are
the antennæ. A poor ant without antennæ is as lost as a blind man who is
also deaf and dumb. This appears from its complete social inactivity,
its isolation, its incapacity to guide itself and to find its food. It
can, therefore, be boldly supposed that the antennæ and their power of
smell, as much on contact as at a distance, constitute the social sense
of ants, the sense which allows them to recognise one another, to tend
to their larvæ, and mutually help one another, and also the sense which
awakens their greedy appetites, their violent hatred for every being
foreign to the colony, the sense which principally guides them--a little
helped by vision, especially in certain species--in the long and patient
travels which they have to undertake, which makes them find their way
back, find their plant-lice, and all their other means of subsistence.
As the philosopher Herbert Spencer has well pointed out, the visceral
sensations of man, and those internal senses which, like smell, can only
make an impression of one kind as regards space--two simultaneous odours
can only be appreciated by us as a mixture--are precisely those by which
we can gain little or no information relative to space. Our vision, on
the contrary, which localises the rays from various distant points of
space on various distinct points of our retina at the same time, is our
most relational sense, that which gives us the most vast ideas of space.
But the antennæ of insects are an olfactory organ turned inside out,
prominent in space, and, further, very mobile. This allows us to suppose
that the sense of smell may be much more relational than ours, that the
sensations thence derived give them ideas of space and of direction
which may be qualitatively different from ours.
Taste exists in insects, and has been very widely written on, but
somewhat inconclusively. The organs of taste probably are to be found in
the jaws and at the base of the tongue. This sense can be observed in
ants, bees, and wasps; and everyone has seen how caterpillars especially
recognise by taste the plants which suit them.
Much has been written on the hearing of insects; but, in my judgment,
only crickets and several other insects of that class appear to perceive
sounds. Erroneous views have been due to confusing hearing with
mechanical vibrations.
We must not forget that the specialisation of the organ of hearing has
reached in man a delicacy of detail which is evidently not found again
in lower vertebrates.
Pain is much less developed in insects than in warm-blooded vertebrates.
Otherwise, one could not see either an ant, with its abdomen or antennæ
cut off, gorge itself with honey; or a humble-bee, in which the antennæ
and all the front of the head had been removed, go to find and pillage
flowers; or a spider, the foot of which had been broken, feed
immediately on this, its own foot, as I myself have seen; or, finally, a
caterpillar, wounded at the "tail" end, devour itself, beginning behind,
as I have observed more than once.
_IV.--Insect Reason and Passions_
Insects reason, and the most intelligent among them, the social
hymenoptera, especially the wasps and ants, even reason much more than
one is tempted to believe when one observes the regularly recurring
mechanism of their instincts. To observe and understand these
reasonings well, it is necessary to mislead their instinct. Further, one
may remark little bursts of plastic judgment, of combinations--extremely
limited, it is true--which, in forcing them an instant from the beaten
track of their automatism, help them to overcome difficulties, and to
decide between two dangers. From the point of view of instinct and
intelligence, or rather of reason, there are not, therefore, absolute
contrasts between the insect, the mammal, and the man.
Finally, insects have passions which are more or less bound up with
their instincts. And these passions vary enormously, according to the
species. I have noted the following passions or traits of character
among ants: choler, hatred, devotion, activity, perseverance, and
gluttony. I have added thereto the discouragement which is sometimes
shown in a striking manner at the time of a defeat, and which can become
real despair; the fear which is shown among ants when they are alone,
while it disappears when they are numerous. I can add further the
momentary temerity whereby certain ants, knowing the enemy to be
weakened and discouraged, hurl themselves alone in the midst of the
black masses of enemies larger than themselves, hustling them without
taking the least further precaution.
When we study the manners of an insect, it is necessary for us to take
account of its mental faculties as well as of its sense organs.
Intelligent insects make better use of their senses, especially by
combining them in various ways. It is possible to study such insects in
their homes in a more varied and more complete manner, allowing greater
accuracy of observations.
GALILEO
Dialogues on the System of the World
Galileo Galilei, famous as an astronomer and as an experimental
physicist, was born at Pisa, in Italy, Feb. 18, 1564. His talents
were most multifarious and remarkable; but his mathematical and
mechanical genius was dominant from the first. As a child he
constructed mechanical toys, and as a young man he made one of his
most important discoveries, which was that of the pendulum as an
agent in the measurement of time, and invented the hydrostatic
balance, by which the specific gravity of solid bodies might be
ascertained. At the age of 24 a learned treatise on the centre of
gravity of solids led to a lectureship at Pisa University. Driven
from Pisa by the enmity of Aristotelians, he went to Padua
University, where he invented a kind of thermometer, a proportional
compass, a microscope, and a telescope. The last invention bore
fruit in astronomical discoveries, and in 1610 he discovered four
of the moons of Jupiter. His promulgation of the Copernican
doctrine led to renewed attacks by the Aristotelians, and to
censure by the Inquisition. (See Religion, vol. xiii.)
Notwithstanding this censure, he published in 1632 his "Dialogues
on the System of the World." The interlocutors in the "Dialogues,"
with the exception of Salviatus, who expounds the views of the
author himself, represent two of Galileo's early friends. For the
"Dialogues" he was sentenced by the Inquisition to incarceration at
its pleasure, and enjoined to recite penitential psalms once a week
for three years. His life thereafter was full of sorrow, and in
1637 blindness added to his woes; but the fire of his genius still
burnt on till his death on January 8, 1642.
_Does the Earth Move_
SALVIATUS: Now, let Simplicius propound those doubts which dissuade him
from believing that the earth may move, as the other planets, round a
fixed centre.
SIMPLICIUS: The first and greatest difficulty is that it is impossible
both to be in a centre and to be far from it. If the earth move in a
circle it cannot remain in the centre of the zodiac; but Aristotle,
Ptolemy and others have proved that it is in the centre of the zodiac.
SALVIATUS: There is no question that the earth cannot be in the centre
of a circle round whose circumference it moves. But tell me what centre
do you mean?
SIMPLICIUS: I mean the centre of the universe, of the whole world, of
the starry sphere.
SALVIATUS: No one has ever proved that the universe is finite and
figurative; but granting that it is finite and spherical, and has
therefore a centre, we have still to give reasons why we should believe
that the earth is at its centre.
SIMPLICIUS: Aristotle has proved in a hundred ways that the universe is
finite and spherical.
SALVIATUS: Aristotle's proof that the universe was finite and spherical
was derived essentially from the consideration that it moved; and seeing
that centre and figure were inferred by Aristotle from its mobility, it
will be reasonable if we endeavour to find from the circular motions of
mundane bodies the centre's proper place. Aristotle himself came to the
conclusion that all the celestial spheres revolve round the earth, which
is placed at the centre of the universe. But tell me, Simplicius,
supposing Aristotle found that one of the two propositions must be
false, and that either the celestial spheres do not revolve or that the
earth is not the centre round which they revolve, which proposition
would he prefer to give up?
SIMPLICIUS: I believe that the Peripatetics----
SALVIATUS: I do not ask the Peripatetics, I ask Aristotle. As for the
Peripatetics, they, as humble vassals of Aristotle, would deny all the
experiments and all the observations in the world; nay, would also
refuse to see them, and would say that the universe is as Aristotle
writeth, and not as Nature will have it; for, deprived of the shield of
his authority, with what do you think they would appear in the field?
Tell me, therefore, what Aristotle himself would do.
SIMPLICIUS: To tell you the truth, I do not know how to decide which is
the lesser inconvenience.
SALVIATUS: Seeing you do not know, let us examine which would be the
more rational choice, and let us assume that Aristotle would have chosen
so. Granting with Aristotle that the universe has a spherical figure and
moveth circularly round a centre, it is reasonable to believe that the
starry orbs move round the centre of the universe or round some separate
centre?
SIMPLICIUS: I would say that it were much more reasonable to believe
that they move with the universe round the centre of the universe.
SALVIATUS: But they move round the sun and not round the earth;
therefore the sun and not the earth is the centre of the universe.
SIMPLICIUS: Whence, then, do you argue that it is the sun and not the
earth that is the centre of the planetary revolutions?
SALVIATUS: I infer that the earth is not the centre of the planetary
revolutions because the planets are at different times at very different
distances from the earth. For instance, Venus, when it is farthest off,
is six times more remote from us than when it is nearest, and Mars rises
almost eight times as high at one time as at another.
SIMPLICIUS: And what are the signs that the planets revolve round the
sun as centre?
SALVIATUS: We find that the three superior planets--Mars, Jupiter, and
Saturn--are always nearest to the earth when they are in opposition to
the sun, and always farthest off when they are in conjunction; and so
great is this approximation and recession that Mars, when near, appears
very nearly sixty times greater than when remote. Venus and Mercury also
certainly revolve round the sun, since they never move far from it, and
appear now above and now below it.
SAGREDUS: I expect that more wonderful things depend on the annual
revolution than upon the diurnal rotation of the earth.
SALVIATUS: YOU do not err therein. The effect of the diurnal rotation of
the earth is to make the universe seem to rotate in the opposite
direction; but the annual motion complicates the particular motions of
all the planets. But to return to my proposition. I affirm that the
centre of the celestial convolutions of the five planets--Saturn,
Jupiter, Mars, Venus, and Mercury, and likewise of the earth--is the
sun.
As for the moon, it goes round the earth, and yet does not cease to go
round the sun with the earth. It being true, then, that the five planets
do move about the sun as a centre, rest seems with so much more reason
to belong to the said sun than to the earth, inasmuch as in a movable
sphere it is more reasonable that the centre stand still than any place
remote from the centre.
To the earth, therefore, may a yearly revolution be assigned, leaving
the sun at rest. And if that be so, it follows that the diurnal motion
likewise belongs to the earth; for if the sun stood still and the earth
did not rotate, the year would consist of six months of day and six
months of night. You may consider, likewise, how, in conformity with
this scheme, the precipitate motion of twenty-four hours is taken away
from the universe; and how the fixed stars, which are so many suns, are
made, like our sun, to enjoy perpetual rest.
SAGREDUS: The scheme is simple and satisfactory; but, tell me, how is it
that Pythagoras and Copernicus, who first brought it forward, could make
so few converts?
SALVIATUS: If you know what frivolous reasons serve to make the vulgar,
contumacious and indisposed to hearken, you would not wonder at the
paucity of converts. The number of thick skulls is infinite, and we need
neither record their follies nor endeavour to interest them in subtle
and sublime ideas. No demonstrations can enlighten stupid brains.
My wonder, Sagredus, is different from yours. You wonder that so few are
believers in the Pythagorean hypothesis; I wonder that there are any to
embrace it. Nor can I sufficiently admire the super-eminence of those
men's wits that have received and held it to be true, and with the
sprightliness of their judgments have offered such violence to their
senses that they have been able to prefer that which their reason
asserted to that which sensible experience manifested. I cannot find any
bounds for my admiration how that reason was able, in Aristarchus and
Copernicus, to commit such a rape upon their senses, as in despite
thereof to make herself mistress of their credulity.
SAGREDUS: Will there still be strong opposition to the Copernican
system?
SALVIATUS: Undoubtedly; for there are evident and sensible facts to
oppose it, requiring a sense more sublime than the common and vulgar
senses to assist reason.
SAGREDUS: Let us, then, join battle with those antagonistic facts.
SALVIATUS: I am ready. In the first place, Mars himself charges hotly
against the truth of the Copernican system. According to the Copernican
system, that planet should appear sixty times as large when at its
nearest as when at its farthest; but this diversity of magnitude is not
to be seen. The same difficulty is seen in the case of Venus. Further,
if Venus be dark, and shine only with reflected light, like the moon, it
should show lunar phases; but these do not appear.
Further, again, the moon prevents the whole order of the Copernican
system by revolving round the earth instead of round the sun. And there
are other serious and curious difficulties admitted by Copernicus
himself. But even the three great difficulties I have named are not
real. As a matter of fact, Mars and Venus do vary in magnitude as
required by theory, and Venus does change its shape exactly like the
moon.
SAGREDUS: But how came this to be concealed from Copernicus and revealed
to you?
SIR FRANCIS GALTON
Essays in Eugenics
Sir Francis Galton, born at Birmingham, England, in 1822, was a
grandson of Dr. Erasmus Darwin. He graduated from Trinity College,
Cambridge, in 1844. Galton travelled in the north of Africa, on the
White Nile and in the western portion of South Africa between 1844
and 1850. Like his immortal cousin, Charles Darwin, Sir Francis
Galton is a striking instance of a man of great and splendid
inheritance, who, also inheriting wealth, devotes it and his powers
to the cause of humanity. He published several books on heredity,
the first of which was "Hereditary Genius." The next "Inquiries
into Human Faculty," which was followed by "Natural Inheritance."
The "Essays in Eugenics" include all the most recent work of Sir
Francis Galton since his return to the subject of eugenics in 1901.
This volume has just been published by the Eugenics Education
Society, of which Sir Francis Galton is the honorary president. As
epitomised for this work, the "Essays" have been made to include a
still later study by the author, which will be included in future
editions of the book. The epitome has been prepared by special
permission of the Eugenics Education Society, and those responsible
hope that it will serve in some measure to neutralise the
outrageous, gross, and often wilful misrepresentations of eugenics
of which many popular writers are guilty.
_I.--The Aims and Methods of Eugenics_
The following essays help to show something of the progress of eugenics
during the last few years, and to explain my own views upon its aims and
methods, which often have been, and still sometimes are, absurdly
misrepresented. The practice of eugenics has already obtained a
considerable hold on popular estimation, and is steadily acquiring the
status of a practical question, and not that of a mere vision in Utopia.
The power by which eugenic reform must chiefly be effected is that of
public opinion, which is amply strong enough for that purpose whenever
it shall be roused. Public opinion has done as much as this on many past
occasions and in various countries, of which much evidence is given in
the essay on restrictions in marriage. It is now ordering our acts more
intimately than we are apt to suspect, because the dictates of public
opinion become so thoroughly assimilated that they seem to be the
original and individual to those who are guided by them. By comparing
the current ideas at widely different epochs and under widely different
civilisations, we are able to ascertain what part of our convictions is
really innate and permanent, and what part has been acquired and is
transient.
It is, above all things, needful for the successful progress of eugenics
that its advocates should move discreetly and claim no more efficacy on
its behalf than the future will justify; otherwise a reaction will be
justified. A great deal of investigation is still needed to show the
limit of practical eugenics, yet enough has been already determined to
justify large efforts being made to instruct the public in an
authoritative way, with the results hitherto obtained by sound
reasoning, applied to the undoubted facts of social experience.
The word "eugenics" was coined and used by me in my book "Human
Faculty," published as long ago as 1883. In it I emphasised the
essential brotherhood of mankind, heredity being to my mind a very real
thing; also the belief that we are born to act, and not to wait for help
like able-bodied idlers, whining for doles. Individuals appear to me as
finite detachments from an infinite ocean of being, temporarily endowed
with executive powers. This is the only answer I can give to myself in
reply to the perpetually recurring questions of "why? whence? and
whither?" The immediate "whither?" does not seem wholly dark, as some
little information may be gleaned concerning the direction in which
Nature, so far as we know of it, is now moving--namely, towards the
evolution of mind, body, and character in increasing energy and
co-adaptation.
The ideas have long held my fancy that we men may be the chief, and
perhaps the only executives on earth; that we are detached on active
service with, it may be only illusory, powers of free-will. Also that we
are in some way accountable for our success or failure to further
certain obscure ends, to be guessed as best we can; that though our
instructions are obscure they are sufficiently clear to justify our
interference with the pitiless course of Nature whenever it seems
possible to attain the goal towards which it moves by gentler and
kindlier ways.
There are many questions which must be studied if we are to be guided
aright towards the possible improvement of mankind under the existing
conditions of law and sentiment. We must study human variety, and the
distribution of qualities in a nation. We must compare the
classification of a population according to social status with the
classification which we would make purely in terms of natural quality.
We must study with the utmost care the descent of qualities in a
population, and the consequences of that marked tendency to marriage
within the class which distinguishes all classes. Something is to be
learnt from the results of examinations in universities and colleges.
It is desirable to study the degree of correspondence that may exist
between promise in youth, as shown in examinations, and subsequent
performance. Let me add that I think the neglect of this inquiry by the
vast army of highly educated persons who are connected with the present
huge system of competitive examination to be gross and unpardonable.
Until this problem is solved we cannot possibly estimate the value of
the present elaborate system of examinations.
_II.--Restrictions in Marriage_
It is necessary to meet an objection that has been repeatedly urged
against the possible adoption of any system of eugenics, namely, that
human nature would never brook interference with the freedom of
marriage. But the question is how far have marriage restrictions proved
effective when sanctified by the religion of the time, by custom, and by
law. I appeal from armchair criticism to historical facts. It will be
found that, with scant exceptions, marriage customs are based on social
expediency and not on natural instincts. This we learn when we study the
fact of monogamy, and the severe prohibition of polygamy, in many times
and places, due not to any natural instinct against the practice, but to
consideration of the social well-being. We find the same when we study
endogamy, exogamy, Australian marriages, and the control of marriage by
taboo.
The institution of marriage, as now sanctified by religion and
safeguarded by law in the more highly civilised nations, may not be
ideally perfect, nor may it be universally accepted in future times, but
it is the best that has hitherto been devised for the parties primarily
concerned, for their children, for home life, and for society. The
degree of kinship within which marriage is prohibited is, with one
exception, quite in accordance with modern sentiment, the exception
being the disallowal of marriage with the sister of a deceased wife, the
propriety of which is greatly disputed and need not be discussed here.
The marriage of a brother and sister would excite a feeling of loathing
among us that seems implanted by nature, but which, further inquiry will
show, has mainly arisen from tradition and custom.
The evidence proves that there is no instinctive repugnance felt
universally by man to marriage within the prohibited degrees, but that
its present strength is mainly due to what I may call immaterial
considerations. It is quite conceivable that a non-eugenic marriage
should hereafter excite no less loathing than that of a brother and
sister would do now.
The dictates of religion in respect to the opposite duties of leading
celibate lives, and of continuing families, have been contradictory. In
many nations it is and has been considered a disgrace to bear no
children, and in other nations celibacy has been raised to the rank of a
virtue of the highest order. During the fifty or so generations that
have elapsed since the establishment of Christianity, the nunneries and
monasteries, and the celibate lives of Catholic priests, have had vast
social effects, how far for good and how far for evil need not be
discussed here. The point I wish to enforce is the potency, not only of
the religious sense in aiding or deterring marriage, but more especially
the influence and authority of ministers of religion in enforcing
celibacy. They have notoriously used it when aid has been invoked by
members of the family on grounds that are not religious at all, but
merely of family expediency. Thus at some times and in some Christian
nations, every girl who did not marry while still young was practically
compelled to enter a nunnery, from which escape was afterwards
impossible.
It is easy to let the imagination run wild on the supposition of a
whole-hearted acceptance of eugenics as a national religion; that is, of
the thorough conviction by a nation that no worthier object exists for
man than the improvement of his own race, and when efforts as great as
those by which nunneries and monasteries were endowed and maintained
should be directed to fulfil an opposite purpose. I will not enter
further into this. Suffice it to say, that the history of conventual
life affords abundant evidence on a very large scale of the power of
religious authority in directing and withstanding the tendencies of
human nature towards freedom in marriage.
Seven different forms of marriage restriction may be cited to show what
is possible. They are monogamy, endogamy, exogamy, Australian marriages,
taboo, prohibited degrees, and celibacy. It can be shown under each of
these heads how powerful are the various combinations of immaterial
motives upon marriage selection, how they may all become hallowed by
religion, accepted as custom, and enforced by law. Persons who are born
under their various rules live under them without any objection. They
are unconscious of their restrictions, as we are unaware of the tension
of the atmosphere. The subservience of civilised races to their several
religious superstitions, customs, authority, and the rest, is frequently
as abject as that of barbarians.
The same classes of motives that direct other races direct ours; so a
knowledge of their customs helps us to realise the wide range of what we
may ourselves hereafter adopt, for reasons as satisfactory to us in
those future times, as theirs are or were to them at the time when they
prevailed.
_III.--Eugenic Qualities of Primary Importance_
The following is offered as a contribution to the art of justly
appraising the eugenic values of different qualities. It may fairly be
assumed that the presence of certain inborn traits is requisite before a
claim to eugenic rank can be justified, because these qualities are
needed to bring out the full values of such special faculties as broadly
distinguish philosophers, artists, financiers, soldiers, and other
representative classes. The method adopted for discovering the qualities
in question is to consider groups of individuals, and to compare the
qualities that distinguish such groups as flourish or prosper from
others of the same kind that decline or decay. This method has the
advantage of giving results more free from the possibility of bias than
those derived from examples of individual cases.
In what follows I shall use the word "community" in its widest sense,
as including any group of persons who are connected by a common
interest--families, schools, clubs, sects, municipalities, nations, and
all intermediate social units. Whatever qualities increase the
prosperity of most or every one of these, will, as I hold, deserve a
place in the first rank of eugenic importance.
Most of us have experience, either by direct observation or through
historical reading, of the working of several communities, and are
capable of forming a correct picture in our minds of the salient
characteristics of those that, on the one hand, are eminently
prosperous, and of those that, on the other hand, are as eminently
decadent. I have little doubt that the reader will agree with me that
the members of prospering communities are, as a rule, conspicuously
strenuous, and that those of decaying or decadent ones are conspicuously
slack. A prosperous community is distinguished by the alertness of its
members, by their busy occupations, by their taking pleasure in their
work, by their doing it thoroughly, and by an honest pride in their
community as a whole. The members of a decaying community are, for the
most part, languid and indolent; their very gestures are dawdling and
slouching, the opposite of smart. They shirk work when they can do so,
and scamp what they undertake. A prosperous community is remarkable for
the variety of the solid interests in which some or other of its members
are eagerly engaged, but the questions that agitate a decadent community
are for the most part of a frivolous order.
Prosperous communities are also notable for enjoyment of life; for
though their members must work hard in order to procure the necessary
luxuries of an advanced civilisation, they are endowed with so large a
store of energy that, when their daily toil is over, enough of it
remains unexpended to allow them to pursue their special hobbies during
the remainder of the day. In a decadent community the men tire easily,
and soon sink into drudgery; there is consequently much languor among
them, and little enjoyment of life.
I have studied the causes of civic prosperity in various directions and
from many points of view, and the conclusion at which I have arrived is
emphatic, namely, that chief among those causes is a large capacity for
labour--mental, bodily, or both--combined with eagerness for work. The
course of evolution in animals shows that this view is correct in
general. The huge lizards, incapable of rapid action, unless it be brief
in duration and associated with long terms of repose, have been
supplanted by birds and mammals possessed of powers of long endurance.
These latter are so constituted as to require work, becoming restless
and suffering in health when precluded from exertion.
We must not, however, overlook the fact that the influence of
circumstance on a community is a powerful factor in raising its tone. A
cause that catches the popular feeling will often rouse a potentially
capable nation from apathy into action. A good officer, backed by
adequate supplies of food and with funds for the regular payment of his
troops, will change a regiment even of ill-developed louts and hooligans
into a fairly smart and well-disciplined corps. But with better material
as a foundation, the influence of a favourable environment is
correspondingly increased, and is less liable to impairment whenever the
environment changes and becomes less propitious. Hence, it follows that
a sound mind and body, enlightened, I should add, with an intelligence
above the average, and combined with a natural capacity and zeal for
work, are essential elements in eugenics. For however famous a man may
become in other respects, he cannot, I think, be justly termed eugenic
if deficient in the qualities I have just named.
Eugenists justly claim to be true philanthropists, or lovers of mankind,
and should bestir themselves in their special province as eagerly as
the philanthropists, in the current and very restricted meaning of that
word, have done in theirs. They should interest themselves in such
families of civic worth as they come across, especially in those that
are large, making friends both with the parents and the children, and
showing themselves disposed to help to a reasonable degree, as
opportunity may offer, whenever help is really needful. They should
compare their own notes with those of others who are similarly engaged.
They should regard such families as an eager horticulturist regards beds
of seedlings of some rare variety of plant, but with an enthusiasm of a
far more patriotic kind. For, since it has been shown that about 10 per
cent. of the individuals born in one generation provide half the next
generation, large families that are also eugenic may prove of primary
importance to the nation and become its most valuable asset.
_IV.--Practical Eugenics_
The following are some views of my own relating to that large province
of eugenics which is concerned with favouring the families of those who
are exceptionally fit for citizenship. Consequently, little or nothing
will here be said relating to what has been well termed by Dr. Saleeby
"negative" eugenics, namely, the hindrance of the marriages and the
production of offspring by the exceptionally unfit. The latter is
unquestionably the more pressing subject, but it will soon be forced on
the attention of the legislature by the recent report of the Royal
Commission on the Feeble-minded.
Whatever scheme of action is proposed for adoption must be neither
Utopian nor extravagant, but accordant throughout with British sentiment
and practice.
By "worth" I mean the civic worthiness, or the value to the state, of a
person. Speaking only for myself, if I had to classify persons according
to worth, I should consider each of them under the three heads of
physique, ability and character, subject to the provision that
inferiority in any one of the three should outweigh superiority in the
other two. I rank physique first, because it is not only very valuable
in itself and allied to many other good qualities, but has the
additional merit of being easily rated. Ability I place second on
similar grounds, and character third, though in real importance it
stands first of all.
The power of social opinion is apt to be underrated rather than
overrated. Like the atmosphere which we breathe and in which we move,
social opinion operates powerfully without our being conscious of its
weight. Everyone knows that governments, manners, and beliefs which were
thought to be right, decorous, and true at one period have been judged
wrong, indecorous, and false at another; and that views which we have
heard expressed by those in authority over us in early life tend to
become axiomatic and unchangeable in mature life.
In circumscribed communities especially, social approval and disapproval
exert a potent force. Is it, then, I ask, too much to expect that when a
public opinion in favour of eugenics has once taken sure hold of such
communities, the result will be manifested in sundry and very effective
modes of action which are as yet untried?
Speaking for myself only, I look forward to local eugenic action in
numerous directions, of which I will now specify one. It is the
accumulation of considerable funds to start young couples of "worthy"
qualities in their married life, and to assist them and their families
at critical times. The charitable gifts to those who are the reverse of
"worthy" are enormous in amount. I am not prepared to say how much of
this is judiciously spent, or in what ways, but merely quote the fact to
justify the inference that many persons who are willing to give freely
at the prompting of a sentiment based upon compassion might be
persuaded to give largely also in response to the more virile desire of
promoting the natural gifts and the national efficiency of future
generations.
_V.--Eugenics as a Factor in Religion_
Eugenics strengthen the sense of social duty in so many important
particulars that the conclusions derived from its study ought to find a
welcome home in every tolerant religion. It promotes a far-sighted
philanthropy, the acceptance of parentage as a serious responsibility,
and a higher conception of patriotism. The creed of eugenics is founded
upon the idea of evolution; not on a passive form of it, but on one that
can, to some extent, direct its own course.
Purely passive, or what may be styled mechanical evolution displays the
awe-inspiring spectacle of a vast eddy of organic turmoil, originating
we know not how, and travelling we know not whither. It forms a
continuous whole, but it is moulded by blind and wasteful
processes--namely, by an extravagant production of raw material and the
ruthless rejection of all that is superfluous, through the blundering
steps of trial and error.
The condition at each successive moment of this huge system, as it
issues from the already quiet past and is about to invade the still
undisturbed future, is one of violent internal commotion. Its elements
are in constant flux and change.
Evolution is in any case a grand phantasmagoria, but it assumes an
infinitely more interesting aspect under the knowledge that the
intelligent action of the human will is, in some small measure, capable
of guiding its course. Man has the power of doing this largely so far as
the evolution of humanity is concerned; he has already affected the
quality and distribution of organic life so widely that the changes on
the surface of the earth, merely through his disforestings and
agriculture, would be recognisable from a distance as great as that of
the moon.
As regards the practical side of eugenics, we need not linger to reopen
the unending argument whether man possesses any creative power of will
at all, or whether his will is not also predetermined by blind forces or
by intelligent agencies behind the veil, and whether the belief that man
can act independently is more than a mere illusion.
Eugenic belief extends the function of philanthropy to future
generations; it renders its action more pervading than hitherto, by
dealing with families and societies in their entirety, and it enforces
the importance of the marriage covenant by directing serious attention
to the probable quality of the future offspring. It sternly forbids all
forms of sentimental charity that are harmful to the race, while it
eagerly seeks opportunity for acts of personal kindness. It strongly
encourages love and interest in family and race. In brief, eugenics is a
virile creed, full of hopefulness, and appealing to many of the noblest
feelings of our nature.
ERNST HAECKEL
The Evolution of Man
Ernst Haeckel, who was born in Potsdam, Germany, Feb. 16, 1834,
descends from a long line of lawyers and politicians. To his
father's annoyance, he turned to science, and graduated in
medicine. After a long tour in Italy in 1859, during which he
wavered between art and science, he decided for zoology, and made a
masterly study of a little-known group of sea-animalcules, the
Radiolaria. In 1861 he began to teach zoology at Jena University.
Darwin's "Origin of Species" had just been translated into German,
and he took up the defence of Darwinism against almost the whole of
his colleagues. His first large work on evolution, "General
Morphology," was published in 1866. He has since published
forty-two distinct works. He is not only a master of zoology, but
has a good command of botany and embryology. Haeckel's "Evolution
of Man" (Anthropogenie), is generally accepted as being his most
important production. Published in 1874, at a time when the theory
of natural evolution had few supporters in Germany, the work was
hailed with a storm of controversy, one celebrated critic declaring
that it was a blot on the escutcheon of Germany. From the hands of
English scientists, however, the treatise received a warm welcome.
Darwin said he would probably never have written his "Descent of
Man" had Haeckel published his work earlier.
_I.--The Science of Man_
The natural history of mankind, or anthropology, must always excite the
most lively interest, and no part of the science is more attractive than
that which deals with the question of man's origin. In order to study
this with full profit, we must combine the results of two sciences,
ontogeny (or embryology) and phylogeny (the science of evolution). We do
this because we have now discovered that the forms through which the
embryo passes in its development correspond roughly to the series of
forms in its ancestral development. The correspondence is by no means
complete or precise, since the embryonic life itself has been modified
in the course of time; but the general law is now very widely accepted.
I have called it "the biogenetic law," and will constantly appeal to it
in the course of this study.
It is only in recent times that the two sciences have advanced
sufficiently to reveal the correspondence of the two series of forms.
Aristotle provided a good foundation for embryology, and made some
interesting discoveries, but no progress was made in the science for
2,000 years after him. Then the Reformation brought some liberty of
research, and in the seventeenth century several works were written on
embryology.
For more than a hundred years the science was still hampered by the lack
of good microscopes. It was generally believed that all the organs of
the body existed, packed in a tiny point of space, in the germ. About
the middle of the eighteenth century, Caspar Friedrich Wolff discovered
the true development; but his work was ignored, and it was only fifty
years later that modern embryology began to work on the right line. K.E.
von Baer made it clear that the fertilised ovum divides into a group of
cells, and that the various organs of the body are developed from these
layers of cells, in the way I shall presently describe.
The science of phylogeny, or, as it is popularly called, the evolution
of species, had an equally slow growth. On the ground of the Mosaic
narrative, no less than in view of the actual appearance of the living
world, the great naturalist Linné (1735) set up the dogma of the
unchangeability of species. Even when quite different remains of animals
were discovered by the advancing science of geology, they were forced
into the existing narrow framework of science by Cuvier. Sir Charles
Lyell completely undid the fallacious work of Cuvier, but in the
meantime the zoologists themselves were moving toward the doctrine of
evolution.
Jean Lamarck made the first systematic attempt to expound the theory in
his "Zoological Philosophy" (1809). He suggested that animals modified
their organs by use or disuse, and that the effect of this was
inherited. In the course of time these inherited modifications reached
such a pitch that the organism fell into a new "species." Goethe also
made some remarkable contributions to the science of evolution. But it
was reserved for Charles Darwin to win an enduring place in science for
the theory. "The Origin of Species" (1859) not only sustained it with a
wealth of positive knowledge which Lamarck did not command, but it
provided a more luminous explanation in the doctrine of natural
selection. Huxley (1863) followed with an application of the law to man,
and in 1866 I gave a comprehensive sketch of its application throughout
the whole animal world. In 1874 I published the first edition of the
present work.
The doctrine of evolution is now a vital part of biology, and we might
accept the evolution of man as a special deduction from the general law.
Three great groups of evidence impose that law on us. The first group
consists of the facts of palæontology, or the fossil record of past
animal life. Imperfect as the record is, it shows us a broad divergence
of successively changing types from a simple common root, and in some
cases exhibits the complete transition from one type to another. The
next document is the evidence of comparative anatomy. This science
groups the forms of living animals in such a way that we seem to have
the same gradual divergence of types from simple common ancestors. In
particular, it discovers certain rudimentary organs in the higher
animals, which can only be understood as the shrunken relics of organs
that were once useful to a remote ancestor. Thus, man has still the
rudiment of the third eyelid of his shark-ancestor. The third document
is the evidence of embryology, which shows us the higher organism
substantially reproducing, in its embryonic development, the long
series of ancestral forms.
_II.--Man's Embryonic Development_
The first stage in the development of any animal is the tiny speck of
plasm, hardly visible to the naked eye, which we call the ovum, or
egg-cell. It is a single cell, recalling the earliest single-celled
ancestor of all animals. In its immature form it is not unlike certain
microscopic animalcules known as _amoeboe_. In its mature form it is
about 1/125th of an inch in diameter.
When the male germ has blended with the female in the ovum, the new cell
slowly divides into two, with a very complicated division of the
material composing its nucleus. The two cells divide into four, the four
into eight, and so on until we have a round cluster of cells, something
like a blackberry in shape.
This _morula_, as I have called it, reproduces the next stage in the
development of life. As all animals pass through it, our biogenetic law
forces us to see in it an ancestral stage; and in point of fact we have
animals of this type living in Nature to-day. The round cluster becomes
filled with fluid, and we have a hollow sphere of cells, which I call
the _blastula_. The corresponding early ancestor I name the _Blastæa_,
and again we find examples of it, like the _Volvox_ of the ponds, in
Nature to-day.
The next step is very important. The hollow sphere closes in on itself,
as when an india rubber ball is pressed into the form of a cup. We have
then a vase-shaped body with two layers of cells, an inner and an outer,
and an opening. The inner layer we call the entoderm, the outer the
ectoderm; and the "primitive mouth" is known as the blastopore. In the
higher animals a good deal of food-yolk is stored up in the germ, and so
the vase-shaped structure has been flattened and altered. It has,
however, been shown that all embryos pass through this stage
(gastrulation), and we again infer the existence of a common ancestor of
that type--the _Gastræa_. The lowest group of many-celled animals--the
corals, jelly-fishes, and anemones--are essentially of that structure.
The embryo now consists of two layers of cells, the "germ-layers," an
inner and outer. As the higher embryo develops, a third layer of cells
now pushes between the two. We may say, broadly, that from this middle
layer are developed most of the animal organs of the body; from the
internal germ-layer is developed the lining of the alimentary canal and
its dependent glands; from the outer layer are formed the skin and the
nervous system--which developed originally in the skin.
The embryo of man and all the other higher animals now develops a
cavity, a pair of pouches, by the folding of the layer at the primitive
mouth. Sir E. Ray Lankester, and Professor Balfour, and other students,
traced this formation through the whole embryonic world, and we are
therefore again obliged to see in it a reminiscence of an ancestral
form--a primitive worm-like animal, of a type we shall see later. The
next step is the formation of the first trace of what will ultimately be
the backbone. It consists at first of a membraneous tube, formed by the
folding of the inner layer along the axis of the embryo-body. Later this
tube will become cartilage, and in the higher animals the cartilage will
give place to bone.
The other organs of the body now gradually form from the germ-layers,
principally by the folding of the layers into tubes. A light area
appears on the surface of the germ. A streak or groove forms along its
axis, and becomes the nerve-cord running along the back. Cube-shaped
structures make their appearance on either side of it; these prove to be
the rudiments of the vertebræ--or separate bones of the backbone--and
gradually close round the cord. The heart is at first merely a
spindle-shaped enlargement of the main ventral blood-vessel. The nose is
at first only a pair of depressions in the skin above the mouth.
When the human embryo is only a quarter of an inch in length, it has
gill-clefts and gill-arches in the throat like a fish, and no limbs. The
heart--as yet with only the simple two-chambered structure of a fish's
heart--is up in the throat--as in the fish--and the principal arteries
run to the gill-slits. These structures never have any utility in man or
the other land-animals, though the embryo always has them for a time.
They point clearly to a fish ancestor.
Later, they break up, the limbs sprout out like blunt fins at the sides,
and the long tail begins to decrease. By the twelfth week the human
frame is perfectly formed, though less than two inches long. Last of
all, it retains its resemblance to the ape. In the embryonic apparatus,
too, man closely resembles the higher ape.
_III.--Our Ancestral Tree_
The series of forms which we thus trace in man's embryonic development
corresponds to the ancestral series which we would assign to man on the
evidence of palæontology and comparative anatomy. At one time, the
tracing of this ancestral series encountered a very serious check. When
we examined the groups of living animals, we found none that illustrated
or explained the passage from the non-backboned--invertebrate--to the
backboned--vertebrate--animals. This gap was filled some years ago by
the discovery of the lancelet--_Amphioxus_--and the young of the
sea-squirt--_Ascidia_. The lancelet has a slender rod of cartilage along
its back, and corresponds very closely with the ideal I have sketched of
our primitive backboned ancestor. It may be an offshoot from the same
group. The sea-squirt further illustrates the origin of the backbone,
since it has a similar rod of cartilage in its youth, and loses it, by
degeneration, in its maturity.
In this way the chief difficulty was overcome, and it was possible to
sketch the probable series of our ancestors. It must be well understood
that not only is the whole series conjectural, but no living animal must
be regarded as an ancestral form. The parental types have long been
extinct, and we may, at the most, use very conservative living types to
illustrate their nature, just as, in the matter of languages, German is
not the parent, but the cousin of Anglo-Saxon, or Greek of Latin. The
original parental languages are lost. But a language like Sanscrit
survives to give us a good idea of the type.
The law of evolution is based on such a mass of evidence that we may
justly draw deductions from it, where the direct evidence is incomplete.
This is especially necessary in the early part of our ancestral tree,
because the fossil record quite fails us. For millions of years the
early soft-bodied animals left no trace in the primitive mud, which time
has hardened into rocks, and we are restricted to the evidence of
embryology and of comparative zoology. This suffices to give us a
general idea of the line of development.
In nature to-day, one of the lowest animal forms is a tiny speck of
living plasm called the _amoeba_. We have still more elementary forms,
such as the minute particles which make up the bluish film on damp
rocks, but they are of a vegetal character, or below it. They give us
some idea of the very earliest forms of life; minute living particles,
with no organs, down to the ten-thousandth part of an inch in diameter.
The amoeba represents the lowest animal, and, as we saw, the ovum in
many cases resembles an amoeba. We therefore take some such one-celled
creature as our first animal ancestor. Taking food in at all parts of
its surface, having no permanent organs of locomotion, and reproducing
by merely splitting into two, it exhibits the lowest level of animal
life.
The next step in development would be the clustering together of these
primitive microbes as they divided. This is actually the stage that
comes next in the development of the germ, and it is the next stage
upward in the existing animal world. We assume that these clusters of
microbes--or cells, as we will now call them--bent inward, as we saw the
embryo do, and became two-layered, cup-shaped organisms, with a hollow
interior (primitive stomach) and an aperture (primitive mouth). The
inner cells now do the work of digestion alone; the outer cells effect
locomotion, by means of lashes like oars, and are sensitive. This is, in
the main, the structure of the next great group of animals, the hydra,
coral, meduca, and anemone. They have remained at this level, though
they have developed, special organs for stinging their prey and bringing
the food into their mouths.
Both zoology and the appearance of the embryo point to a worm-like
animal as the next stage. Constant swimming in the water would give the
animal a definite head, with special groups of nerve-cells, a definite
tail, and a two-sided or evenly-balanced body.
We mean that those animals would be fittest to live, and multiply most,
which developed this organisation. Sense-organs would now appear in the
head, in the form of simple depressions, lined with sensitive cells, as
they do in the embryo; and a clump of nerve-cells within would represent
the primitive brain. In the vast and varied worm-group we find
illustrations of nearly every step in this process of evolution.
The highest type of worm-like creature, the acorn-headed
worm--_Balanoglossus_--takes us an important step further. It has
gill-openings for breathing, and a cord of cartilage down its back. We
saw that the human embryo has a gill-apparatus, and that, comparing the
lancelet and the sea-squirt, the backbone must have begun as a string of
cartilage-cells. We are now on firmer ground, for there is no doubt that
all the higher land-animals come from a fish ancestor. The shark, one of
the most primitive of fishes in organisation, probably best suggests
this ancestor to us. In fact, in the embryonic development of the human
face there is a clear suggestion of the shark.
Up to this period the story of evolution had run its course in the sea.
The area of dry land was now increasing, and certain of the primitive
fishes adapted themselves to living on land. They walked on their fins,
and used their floating-bladders--large air-bladders in the fish, for
rising in the water--to breathe air. We not only have fishes of this
type in Australia to-day, but we have the fossil remains of similar
fishes in the Old Red Sandstone rocks. From mud-fish the amphibian would
naturally develop, as it did in the coal-forest period. Walking on the
fins would strengthen the main stem, the broad paddle would become
useless, and we should get in time the bony five-toed limb. We have many
of these giant salamander forms in the rocks.
The reptile now evolved from the amphibian, and a vast reptile
population spread over the earth. From one of these early reptiles the
birds were evolved. Geology furnishes the missing link between the bird
and the reptile in the _Archæopteryx_, a bird with teeth, claws on its
wings, and a reptilian tail. From another primitive reptile the
important group of the mammals was evolved. We find what seem to be the
transitional types in the rocks of South Africa. The scales gave way to
tufts of hair, the heart evolved a fourth chamber, and thus supplied
purer blood (warm blood), the brain profited by the richer food, and the
mother began to suckle the young. We have still a primitive mammal of
this type in the duck-mole, or duck-billed platypus (_Ornithorhyncus_)
of Australia. There are grounds for thinking that the next stage was an
opossum-like animal, and this led on to the lowest ape-like being, the
lemur. Judging from the fossil remains, the black lemur of Madagascar
best suggests this ancestor.
The apes of the Old and New Worlds now diverged from this level, and
some branch of the former gave rise to the man-like apes and man. In
bodily structure and embryonic development the large apes come very
close to man, and two recent discoveries have put their
blood-relationship beyond question. One is that experiments in the
transfusion of blood show that the blood of the man-like ape and man
have the same action on the blood of lower animals. The other is that we
have discovered, in Java, several bones of a being which stands just
midway between the highest living ape and lowest living race of men.
This ape-man (_Pithecanthropus_) represents the last of our animal and
first of our human ancestors.
_IV.--Evolution of Separate Organs_
So far, we have seen how the human body as a whole develops through a
long series of extinct ancestors. We may now take the various systems of
organs one by one, and, if we are careful to consult embryology as well
as zoology, we can trace the manner of their development. It is, in
accordance with our biogenetic law, the same in the embryo, as a rule,
as in the story of past evolution.
We take first the nervous system. In the lowest animals, as in the early
stages of the embryo, there are no nerve-cells. In the embryo the
nerve-cells develop from the outer, or skin layer, of cells. This,
though strange as regards the human nervous system, is a correct
preservation of the primitive seat of the nerves. It was the surface of
the animal that needed to be sensitive in the primitive organism. Later,
when definite connecting nerves were formed, only special points in the
surface, protected by coverings which did not interfere with the
sensitiveness, needed to be exposed, and the nerves transmitted the
impressions to the central brain.
This development is found in the animal world to-day. In such animals as
the hydra we find the first crude beginning of unorganised nerve-cells.
In the jelly-fish we find nerve-cells clustered into definite sensitive
organs. In the lower worms we have the beginning of organs of smell and
vision. They are at first merely blind, sensitive pits in the skin, as
in the embryo. The ear has a peculiar origin. Up to the fish level there
is no power of hearing. There is merely a little stone rolling in a
sensitive bed, to warn the animal of its movement from side to side. In
the higher animals this evolves into the ear.
The glands of the skin (sweat, fat, tears, etc.) appear at first as
blunt, simple ingrowths. The hair first appears in tufts, representing
the scales, from underneath which they were probably evolved. The thin
coat of hair on the human body to-day is an ancestral inheritance. This
is well shown by the direction of the hairs on the arm. As on the ape's
arm, both on the upper and lower arm, they grow toward the elbow. The
ape finds this useful in rain, using his arms like a thatched roof, and
on our arm this can only be a reminiscence of the habits of an ape
ancestor.
We have seen how the spinal cord first appears as a tube in the axis of
the back, and the cartilaginous column closes round it. All bone appears
first as membrane, then cartilage, and finally ossifies. This is the
order both in past evolution and in present embryonic development. The
brain is at first a bulbous expansion of the spinal nerve-cord. It is at
first simple, but gradually, both in the scale of nature and in the
embryo, divides into five parts. One of these parts, the cerebrum, is
mainly connected with mental life. We find it increasing in size, in
proportion to the animal's intelligence, until in man it comes to cover
the whole of the brain. When we remove it from the head of the mammal,
without killing the animal, we find all mental life suspended, and the
whole vitality used in vegetative functions.
In the evolution of the bony system we find the same correspondence of
embryology and evolution. The main column is at first a rod of
cartilage. In time the separate cubes appear which are to form the
vertebræ of the flexible column. The skull develops in the same way.
Just as the brain is a specially modified part of the nerve-rod, the
skull is only a modified part of the vertebral column. The bones that
compose it are modified vertebræ, as Goethe long ago suspected. The
skull of the shark gives us a hint of the way in which the modification
took place, and the formation of the skull in the embryo confirms it.
That adult man is devoid of that prolongation of the vertebral column
which we call a tail is not a distinctive peculiarity. The higher apes
are equally without it. We find, however, that the human embryo has a
long tail, much longer than the legs, when they are developing. At
times, moreover, children are born with tails--perfect tails, with
nerves and muscles, which they move briskly under emotion, and these
have to be amputated. The development of the limb from the fin offers no
serious difficulty to the osteologist. All the higher animals descend
from a five-toed ancestor. The whale has taken again to the water, and
reconverted its limb into a paddle. The bones of the front feet still
remain under the flesh. Animals of the horse type have had the central
toe strengthened, for running purposes, at the expense of the rest. The
serpent has lost its limbs from disuse, but in the python a rudimentary
limb-bone is still preserved.
The alimentary system, blood-vessel system, and reproductive system
have been evolved gradually in the same way. The stomach is at first the
whole cavity in the animal. Later it becomes a straight, simple tube,
strengthened by a gullet in front. The liver is an outgrowth from this
tube; the stomach proper is a bulbous expansion of its central part,
later provided with a valve. The kidneys are at first simple channels in
the skin for drainage, then closed tubes, which branch out more and
more, and then gather into our compact kidneys. We thus see that the
building up of the human body from a single cell is a substantial
epitome of the long story of evolution, which occupied many millions of
years. We find man bearing in his body to-day traces of organs which
were useful to a remote ancestor, but of no advantage, and often a
source of mischief to himself. We learn that the origin of man, instead
of being placed a few thousand years ago, must be traced back to the
point where, hundreds of thousands of years ago, he diverged from his
ape-cousins, though he retains to-day the plainest traces of that
relationship. Body and mind--for the development of mind follows with
the utmost precision on the development of brain--he is the culmination
of a long process of development. His spirit is a form of energy
inseparably bound up with the substance of his body. His evolution has
been controlled by the same "eternal, iron laws" as the development of
any other body--the laws of heredity and adaptation.
WILLIAM HARVEY
On the Motion of the Heart and Blood
William Harvey, the discoverer of the circulation of the blood, was
born at Folkestone, England, on April 1, 1578. After graduating
from Caius College, Cambridge, he studied at Padua, where he had
the celebrated anatomist, Fabricius of Aquapendente, for his
master. In 1615 he was elected Lumleian lecturer at the College of
Physicians, and three years later was appointed physician
extraordinary to King James I. In 1628, twelve years after his
first statement of it in his lectures, he published at Frankfurt,
in Latin, "An Anatomical Disquisition on the Motion of the Heart
and Blood," in which he maintained that there is a circulation of
the blood. Moreover, he distinguished between the pulmonary
circulation, from the right side of the heart to the left through
the lungs, and the systemic circulation from the left side of the
heart to the right through the rest of the body. Further, he
maintained that it was the office of the heart to maintain this
circulation by its alternate _diastole_ (expansion) and _systole_
(contraction) throughout life. This discovery was, says Sir John
Simon, the most important ever made in physiological science. It is
recorded that after his publication of it Harvey lost most of his
practice. Harvey died on June 3, 1657.
_I.--Motions of the Heart in Living Animals_
When first I gave my mind to vivisections as a means of discovering the
motions and uses of the heart, I found the task so truly arduous that I
was almost tempted to think, with Fracastorius, that the motion of the
heart was only to be comprehended by God. For I could neither rightly
perceive at first when the systole and when the diastole took place, nor
when and where dilation and contraction occurred, by reason of the
rapidity of the motion, which, in many animals, is accomplished in the
twinkling of an eye, coming and going like a flash of lightning. At
length it appeared that these things happen together or at the same
instant: the tension of the heart, the pulse of its apex, which is felt
externally by its striking against the chest, the thickening of its
walls, and the forcible expulsion of the blood it contains by the
constriction of its ventricles.
Hence the very opposite of the opinions commonly received appears to be
true; inasmuch as it is generally believed that when the heart strikes
the breast and the pulse is felt without, the heart is dilated in its
ventricles and is filled with blood. But the contrary of this is the
fact; that is to say, the heart is in the act of contracting and being
emptied. Whence the motion, which is generally regarded as the diastole
of the heart, is in truth its systole. And in like manner the intrinsic
motion of the heart is not the diastole but the systole; neither is it
in the diastole that the heart grows firm and tense, but in the systole;
for then alone when tense is it moved and made vigorous. When it acts
and becomes tense the blood is expelled; when it relaxes and sinks
together it receives the blood in the manner and wise which will by and
by be explained.
From divers facts it is also manifest, in opposition to commonly
received opinions, that the diastole of the arteries corresponds with
the time of the heart's systole; and that the arteries are filled and
distended by the blood forced into them by the contraction of the
ventricles. It is in virtue of one and the same cause, therefore, that
all the arteries of the body pulsate, _viz._, the contraction of the
left ventricle in the same way as the pulmonary artery pulsates by the
contraction of the right ventricle.
I am persuaded it will be found that the motion of the heart is as
follows. First of all, the auricle contracts and throws the blood into
the ventricle, which, being filled, the heart raises itself straightway,
makes all its fibres tense, contracts the ventricles and performs a
beat, by which beat it immediately sends the blood supplied to it by the
auricle into the arteries; the right ventricle sending its charge into
the lungs by the vessel called _vena arteriosa_, but which, in structure
and function, and all things else, is an artery; the left ventricle
sending its charge into the aorta, and through this by the arteries to
the body at large.
The grand cause of hesitation and error in this subject appears to me to
have been the intimate connection between the heart and the lungs. When
men saw both the pulmonary artery and the pulmonary veins losing
themselves in the lungs, of course it became a puzzle to them to know
how the right ventricle should distribute the blood to the body, or the
left draw it from the _venæ cavæ_. Or they have hesitated because they
did not perceive the route by which the blood is transferred from the
veins to the arteries, in consequence of the intimate connection between
the heart and lungs. And that this difficulty puzzled anatomists not a
little when in their dissections they found the pulmonary artery and
left ventricle full of black and clotted blood, plainly appears when
they felt themselves compelled to affirm that the blood made its way
from the right to the left ventricle by sweating through the septum of
the heart.
Had anatomists only been as conversant with the dissection of the lower
animals as they are with that of the human body, the matters that have
hitherto kept them in perplexity of doubt would, in my opinion, have met
them freed from every kind of difficulty. And first in fishes, in which
the heart consists of but a single ventricle, they having no lungs, the
thing is sufficiently manifest. Here the sac, which is situated at the
base of the heart, and is the part analogous to the auricle in man,
plainly throws the blood into the heart, and the heart in its turn
conspicuously transmits it by a pipe or artery, or vessel analogous to
an artery; these are facts which are confirmed by simple ocular
experiment. I have seen, farther, that the same thing obtained most
obviously.
And since we find that in the greater number of animals, in all indeed
at a certain period of their existence, the channels for the
transmission of the blood through the heart are so conspicuous, we have
still to inquire wherefore in some creatures--those, namely, that have
warm blood and that have attained to the adult age, man among the
number--we should not conclude that the same thing is accomplished
through the substance of the lungs, which, in the embryo, and at a time
when the functions of these organs is in abeyance, Nature effects by
direct passages, and which indeed she seems compelled to adopt through
want of a passage by the lungs; or wherefore it should be better (for
Nature always does that which is best) that she should close up the
various open routes which she had formerly made use of in the embryo,
and still uses in all other animals; not only opening up no new apparent
channels for the passage of the blood therefore, but even entirely
shutting up those which formerly existed in the embryos of those animals
that have lungs. For while the lungs are yet in a state of inaction,
Nature uses the two ventricles of the heart as if they formed but one
for the transmission of the blood. The condition of the embryos of those
animals which have lungs is the same as that of those animals which have
no lungs.
Thus, by studying the structure of the animals who are nearer to and
further from ourselves in their modes of life and in the construction of
their bodies, we can prepare ourselves to understand the nature of the
pulmonary circulation in ourselves, and of the systemic circulation
also.
_II.--Systemic Circulation_
What remains to be said is of so novel and unheard of a character that I
not only fear injury to myself from the envy of a few, but I tremble
lest I have mankind at large for my enemies, so much do wont and custom
that become as another nature, and doctrine once sown that hath struck
deep root, and respect for antiquity, influence all men.
And, sooth to say, when I surveyed my mass of evidence, whether derived
from vivisections and my previous reflections on them, or from the
ventricles of the heart and the vessels that enter into and issue from
them, the symmetry and size of these conduits--for Nature, doing nothing
in vain, would never have given them so large a relative size without a
purpose; or from the arrangement and intimate structure of the valves in
particular and of the many other parts of the heart in general, with
many things besides; and frequently and seriously bethought me and long
revolved in my mind what might be the quantity of blood which was
transmitted, in how short a time its passage might be effected and the
like; and not finding it possible that this could be supplied by the
juices of the ingested aliment without the veins on the one hand
becoming drained, and the arteries on the other getting ruptured through
the excessive charge of blood, unless the blood should somehow find its
way from the arteries into the veins, and so return to the right side of
the heart; when I say, I surveyed all this evidence, I began to think
whether there might not be _a motion as it were in a circle_.
Now this I afterwards found to be true; and I finally saw that the
blood, forced by the action of the left ventricle into the arteries, was
distributed to the body at large, and its several parts, in the same
manner as it is sent through the lungs, impelled by the right ventricle
into the pulmonary artery; and that it then passed through the veins and
along the _vena cava_, and so round to the left ventricle in the manner
already indicated; which motion we may be allowed to call circular, in
the same way as Aristotle says that the air and the rain emulate the
circular motion of the superior bodies. For the moist earth, warmed by
the sun, evaporates; the vapours drawn upwards are condensed, and
descending in the form of rain moisten the earth again. And by this
arrangement are generations of living things produced; and in like
manner, too, are tempests and meteors engendered by the circular motion
of the sun.
And so in all likelihood does it come to pass in the body through the
motion of the blood. The various parts are nourished, cherished,
quickened by the warmer, more perfect, vaporous, spirituous, and, as I
may say, alimentive blood; which, on the contrary, in contact with these
parts becomes cooled, coagulated, and, so to speak, effete; whence it
returns to its sovereign, the heart, as if to its source, or to the
inmost home of the body, there to recover its state of excellence or
perfection. Here it resumes its due fluidity, and receives an infusion
of natural heat--powerful, fervid, a kind of treasury of life--and is
impregnated with spirits and, it might be said, with balsam; and thence
it is again dispersed. And all this depends upon the motion and action
of the heart.
_Confirmations of the Theory_
Three points present themselves for confirmation, which, being
established, I conceive that the truth I contend for will follow
necessarily and appear as a thing obvious to all.
The first point is this. The blood is incessantly transmitted by the
action of the heart from the _vena cava_ to the arteries in such
quantity that it cannot be supplied from the ingesta, and in such wise
that the whole mass must very quickly pass through the organ.
Let us assume the quantity of blood which the left ventricle of the
heart will contain when distended to be, say, two ounces (in the dead
body I have found it to contain upwards of two ounces); and let us
suppose, as approaching the truth, that the fourth part of its charge
is thrown into the artery at each contraction. Now, in the course of
half an hour the heart will have made more than one thousand beats.
Multiplying the number of drachms propelled by the number of pulses, we
shall have one thousand half-ounces sent from this organ into the
artery; a larger quantity than is contained in the whole body. This
truth, indeed, presents itself obviously before us when we consider what
happens in the dissection of living animals. The great artery need not
be divided, but a very small branch only (as Galen even proves in regard
to man), to have the whole of the blood in the body, as well that of the
veins as of the arteries, drained away in the course of no long
time--some half hour or less.
The second point is this. The blood, under the influence of the arterial
pulse, enters, and is impelled in a continuous, equable, and incessant
stream through every part and member of the body in much larger quantity
than were sufficient for nutrition, or than the whole mass of fluids
could supply.
I have here to cite certain experiments. Ligatures are either very tight
or of middling tightness. A ligature I designate as tight, or perfect,
when it is drawn so close about an extremity that no vessel can be felt
pulsating beyond it. Such ligatures are employed in the removal of
tumours; and in these cases, all afflux of nutriment and heat being
prevented by the ligature, we see the tumours dwindle and die, and
finally drop off. Now let anyone make an experiment upon the arm of a
man, either using such a fillet as is employed in bloodletting, or
grasping the limb tightly with his hand; let a ligature be thrown about
the extremity and drawn as tightly as can be borne. It will first be
perceived that beyond the ligature the arteries do not pulsate, while
above it the artery begins to rise higher at each diastole and to swell
with a kind of tide as it strove to break through and overcome the
obstacle to its current.
Then let the ligature be brought to that state of middling tightness
which is used in bleeding, and it will be seen that the hand and arm
will instantly become deeply suffused and extended, and the veins show
themselves tumid and knotted. Which is as much as to say that when the
arteries pulsate the blood is flowing through them, but where they do
not pulsate they cease from transmitting anything. The veins again being
compressed, nothing can flow through them; the certain indication of
which is that below the ligature they are much more tumid than above it.
Whence is this blood? It must needs arrive by the arteries. For that it
cannot flow in by the veins appears from the fact that the blood cannot
be forced towards the heart unless the ligature be removed. Further,
when we see the veins below the ligature instantly swell up and become
gorged when from extreme tightness it is somewhat relaxed, the arteries
meanwhile continuing unaffected, this is an obvious indication that the
blood passes from the arteries into the veins, and not from the veins
into the arteries, and that there is either an anastomosis of the two
orders of vessels, or pores in the flesh and solid parts generally that
are permeable to the blood.
And now we understand wherefore in phlebotomy we apply our fillet above
the part that is punctured, not below it. Did the flow come from above,
not from below, the bandage in this case would not only be of no
service, but would prove a positive hindrance. And further, if we
calculate how many ounces flow through one arm or how many pass in
twenty or thirty pulsations under the medium ligature, we shall perceive
that a circulation is absolutely necessary, seeing that the quantity
cannot be supplied immediately from the ingesta, and is vastly more than
can be requisite for the mere nutrition of the parts.
And the third point to be confirmed is this. That the veins return this
blood to the heart incessantly from all parts and members of the body.
This position will be made sufficiently clear from the valves which are
found in the cavities of the veins themselves, from the uses of these,
and from experiments cognisable by the senses. The celebrated Hieronymus
Fabricius, of Aquapendente, first gave representations of the valves in
the veins, which consist of raised or loose portions of the inner
membranes of these vessels of extreme delicacy and a sigmoid, or
semi-lunar shape. Their office is by no means explained when we are told
that it is to hinder the blood, by its weight, from flowing into
inferior parts; for the edges of the valves in the jugular veins hang
downwards, and are so contrived that they prevent the blood from rising
upwards.
The valves, in a word, do not invariably look upwards, but always
towards the trunks of the veins--towards the seat of the heart. They are
solely made and instituted lest, instead of advancing from the extreme
to the central parts of the body, the blood should rather proceed along
the veins from the centre to the extremities; but the delicate valves,
while they readily open in the right direction, entirely prevent all
such contrary motion, being so situated and arranged that if anything
escapes, or is less perfectly obstructed by the flaps of the one above,
the fluid passing, as it were, by the chinks between the flaps, it is
immediately received on the convexity of the one beneath, which is
placed transversely with reference to the former, and so is effectually
hindered from getting any farther. And this I have frequently
experienced in my dissections of veins. If I attempted to pass a probe
from the trunk of the veins into one of the smaller branches, whatever
care I took I found it impossible to introduce it far any way by reason
of the valves; whilst, on the contrary, it was most easy to push it
along in the opposite direction, from without inwards, or from the
branches towards the trunks and roots.
And now I may be allowed to give in brief my view of the circulation of
the blood, and to propose it for general adoption.
_The Conclusion_
Since all things, both argument and ocular demonstration, show that the
blood passes through the lungs and heart by the action of the
ventricles; and is sent for distribution to all parts of the body, where
it makes its way into the veins and pores of the flesh; and then flows
by the veins from the circumference on every side to the centre, from
the lesser to the greater veins; and is by them finally discharged into
the _vena cava_ and right auricle of the heart, and this in such a
quantity or in such a flux and reflux, thither by the arteries, hither
by the veins, as cannot possibly be supplied by the ingesta, and is much
greater than can be required for mere purposes of nutrition; therefore,
it is absolutely necessary to conclude that the blood in the animal body
is impelled in a circle and is in a state of ceaseless motion; and that
this is the act, or function, which the heart performs by means of its
pulse, and that it is the sole and only end of the motion and
contraction of the heart. For it would be very difficult to explain in
any other way to what purpose all is constructed and arranged as we have
seen it to be.
SIR JOHN HERSCHEL
Outlines of Astronomy
Sir John Frederick William Herschel, only child--and, as an
astronomer, almost the only rival--of Sir William Herschel, was
born at Slough, in Ireland, on March 7, 1792. At first privately
educated, in 1813 he graduated from St. John's College, Cambridge,
as senior wrangler and first Smith's prizeman. He chose the law as
his profession; but in 1816 reported that, under his father's
direction, he was going "to take up stargazing." He then began a
re-examination of his father's double stars. In 1825 he wrote that
he was going to take nebulæ under his especial charge. He embarked
in 1833 with his family for the Cape; and his work at Feldhausen,
six miles from Cape Town, marked the beginning of southern sidereal
astronomy. The result of his four years' work there was published
in 1847. From 1855 he devoted himself at Collingwood to the
collection and revival of his father's and his own labours. His
"Outlines of Astronomy," published in 1849, and founded on an
earlier "Treatise on Astronomy" of 1833, was an outstanding
success. Herschel's long and happy life, every day of which added
its share to his scientific services, came to an end on May 11,
1871.
_I.--The Wonders of the Milky Way_
There is no science which draws more largely than does astronomy on that
intellectual liberality which is ready to adopt whatever is demonstrated
or concede whatever is rendered highly probable, however new and
uncommon the points of view may be in which objects the most familiar
may thereby become placed. Almost all its conclusions stand in open and
striking contradiction with those of superficial and vulgar observation,
and with what appears to everyone the most positive evidence of his
senses.
There is hardly anything which sets in a stronger light the inherent
power of truth over the mind of man, when opposed by no motives of
interest or passion, than the perfect readiness with which all its
conclusions are assented to as soon as their evidence is clearly
apprehended, and the tenacious hold they acquire over our belief when
once admitted.
If the comparison of the apparent magnitude of the stars with their
number leads to no immediately obvious conclusion, it is otherwise when
we view them in connection with their local distribution over the
heavens. If indeed we confine ourselves to the three or four brightest
classes, we shall find them distributed with a considerable approach to
impartiality over the sphere; a marked preference, however, being
observable, especially in the southern hemisphere, to a zone or belt
passing through _epsilon_ Orionis and _alpha_ Crucis. But if we take in
the whole amount visible to the naked eye we shall perceive a great
increase of numbers as we approach the borders of the Milky Way. And
when we come to telescopic magnitudes we find them crowded beyond
imagination along the extent of that circle and of the branches which it
sends off from it; so that, in fact, its whole light is composed of
nothing but stars of every magnitude from such as are visible to the
naked eye down to the smallest points of light perceptible with the best
telescopes.
These phenomena agree with the supposition that the stars of our
firmament, instead of being scattered indifferently in all directions
through space, form a stratum of which the thickness is small in
comparison with its length and breadth; and in which the earth occupies
a place somewhere about the middle of its thickness and near the point
where it subdivides into two principal laminæ inclined at a small angle
to each other. For it is certain that to an eye so situated the apparent
density of the stars, supposing them pretty equally scattered through
the space they occupy, would be least in the direction of the visual ray
perpendicular to the lamina, and greatest in that of its breadth;
increasing rapidly in passing from one to the other direction, just as
we see a slight haze in the atmosphere thickening into a decided
fog-bank near the horizon by the rapid increase of the mere length of
the visual ray.
Such is the view of the construction of the starry firmament taken by
Sir William Herschel, whose powerful telescopes first effected a
complete analysis of this wonderful zone, and demonstrated the fact of
its entirely consisting of stars.
So crowded are they in some parts of it that by counting the stars in a
single field of his telescope he was led to conclude that 50,000 had
passed under his review in a zone two degrees in breadth during a single
hour's observation. The immense distances at which the remoter regions
must be situated will sufficiently account for the vast predominance of
small magnitudes which are observed in it.
The process of gauging the heavens was devised by Sir William Herschel
for this purpose. It consisted simply in counting the stars of all
magnitudes which occur in single fields of view, of fifteen minutes in
diameter, visible through a reflecting telescope of 18 inches aperture,
and 20 feet focal length, with a magnifying power of 180 degrees, the
points of observation being very numerous and taken indiscriminately in
every part of the surface of the sphere visible in our latitudes.
On a comparison of many hundred such "gauges," or local enumerations, it
appears that the density of starlight (or the number of stars existing
on an average of several such enumerations in any one immediate
neighbourhood) is least in the pole of the Galactic circle [_i.e._, the
great circle to which the course of the Milky Way most nearly conforms:
_gala_ = milk], and increases on all sides down to the Milky Way itself,
where it attains its maximum. The progressive rate of increase in
proceeding from the pole is at first slow, but becomes more and more
rapid as we approach the plane of that circle, according to a law from
which it appears that the mean density of the stars in the galactic
circle exceeds, in a ratio of very nearly 30 to 1, that in its pole, and
in a proportion of more than 4 to 1 that in a direction 15 degrees
inclined to its plane.
As we ascend from the galactic plane we perceive that the density
decreases with great rapidity. So far we can perceive no flaw in this
reasoning if only it be granted (1) that the level planes are continuous
and of equal density throughout; and (2) that an absolute and definite
limit is set to telescopic vision, beyond which, if stars exist, they
elude our sight, and are to us as if they existed not. It would appear
that, with an almost exactly similar law of apparent density in the two
hemispheres, the southern were somewhat richer in stars than the
northern, which may arise from our situation not being precisely in the
middle of its thickness, but somewhat nearer to its northern surface.
_II.--Penetrating Infinite Space_
When examined with powerful telescopes, the constitution of this
wonderful zone is found to be no less various than its aspect to the
naked eye is irregular. In some regions the stars of which it is
composed are scattered with remarkable uniformity over immense tracts,
while in others the irregularity of their distribution is quite as
striking, exhibiting a rapid succession of closely clustering rich
patches separated by comparatively poor intervals, and indeed in some
instances absolutely dark and _completely_ void of any star even of the
smallest telescopic magnitude. In some places not more than 40 or 50
stars on an average occur in a "gauge" field of 15 minutes, while in
others a similar average gives a result of 400 or 500.
Nor is less variety observable in the character of its different
regions in respect of the magnitude of the stars they exhibit, and the
proportional numbers of the larger and smaller magnitudes associated
together, than in respect of their aggregate numbers. In some, for
instance, extremely minute stars, though never altogether wanting, occur
in numbers so moderate as to lead us irresistibly to the conclusion that
in these regions we are _fairly through_ the starry stratum, since it is
impossible otherwise (supposing their light not intercepted) that the
numbers of the smaller magnitudes should not go on increasing _ad
infinitum_.
In such cases, moreover, the ground of the heavens, as seen between the
stars, is for the most part perfectly dark, which again would not be the
case if innumerable multitudes of stars, too minute to be individually
discernible, existed beyond. In other regions we are presented with the
phenomenon of an almost uniform degree of brightness of the individual
stars, accompanied with a very even distribution of them over the ground
of the heavens, both the larger and smaller magnitudes being strikingly
deficient. In such cases it is equally impossible not to perceive that
we are looking through a sheet of stars nearly of a size and of no great
thickness compared with the distance which separates them from us. Were
it otherwise we should be driven to suppose the more distant stars were
uniformly the larger, so as to compensate by their intrinsic brightness
for their greater distance, a supposition contrary to all probability.
In others again, and that not infrequently, we are presented with a
double phenomenon of the same kind--_viz._, a tissue, as it were, of
large stars spread over another of very small ones, the intermediate
magnitudes being wanting, and the conclusion here seems equally evident
that in such cases we look through two sidereal sheets separated by a
starless interval.
Throughout by far the larger portion of the extent of the Milky Way in
both hemispheres the general blackness of the ground of the heavens on
which its stars are projected, and the absence of that innumerable
multitude and excessive crowding of the smallest visible magnitudes, and
of glare produced by the aggregate light of multitudes too small to
affect the eye singly, which the contrary supposition would appear to
necessitate, must, we think, be considered unequivocal indications that
its dimensions, _in directions where those conditions obtain_, are not
only not infinite, but that the space-penetrating power of our
telescopes suffices fairly to pierce through and beyond it.
It is but right, however, to warn our readers that this conclusion has
been controverted, and that by an authority not lightly to be put aside,
on the ground of certain views taken by Olbers as to a defect of perfect
transparency in the celestial spaces, in virtue of which the light of
the more distant stars is enfeebled more than in proportion to their
distance. The extinction of light thus originating proceeding in
geometrical ratio, while the distance increases in arithmetical, a
limit, it is argued, is placed to the space-penetrating power of
telescopes far within that which distance alone, apart from such
obscuration, would assign.
It must suffice here to observe that the objection alluded to, if
applicable to any, is equally so to every part of the galaxy. We are not
at liberty to argue that at one part of its circumference our view is
limited by this sort of cosmical veil, which extinguishes the smaller
magnitudes, cuts off the nebulous light of distant masses, and closes
our view in impenetrable darkness; while at another we are compelled, by
the clearest evidence telescopes can afford, to believe that star-strewn
vistas _lie open_, exhausting their powers and stretching out beyond
their utmost reach, as is proved by that very phenomenon which the
existence of such a veil would render impossible--_viz._, infinite
increase of number and diminution of magnitude, terminating in complete
irresolvable nebulosity.
Such is, in effect, the spectacle afforded by a very large portion of
the Milky Way in that interesting region near its point of bifurcation
in Scorpio, where, through the hollows and deep recesses of its
complicated structure, we behold what has all the appearance of a wide
and indefinitely prolonged area strewed over with discontinuous masses
and clouds of stars, which the telescope at last refuses to analyse.
Whatever other conclusions we may draw, this must anyhow be regarded as
the direction of the greatest linear extension of the ground-plan of the
galaxy. And it would appear to follow also that in those regions where
that zone is clearly resolved into stars well separated and _seen
projected on a black ground_, and where, by consequence, it is certain,
if the foregoing views be correct, that we look out beyond them into
space, the smallest visible stars appear as such not by reason of
excessive distance, but of inferiority of size or brightness.
_III.--Variable, Temporary and Binary Stars_
Wherever we can trace the law of periodicity we are strongly impressed
with the idea of rotatory or orbitual motion. Among the stars are
several which, though in no way distinguishable from others by any
apparent change of place, nor by any difference of appearance in
telescopes, yet undergo a more or less regular periodical increase and
diminution of lustre, involving in one or two cases a complete
extinction and revival. These are called periodic stars. The longest
known, and one of the most remarkable, is the star _Omicron_ in the
constellation Cetus (sometimes called Mira Ceti), which was first
noticed as variable by Fabricius in 1596. It appears about twelve times
in eleven years, remains at its greatest brightness about a fortnight,
being then on some occasions equal to a large star of the second
magnitude, decreases during about three months, till it becomes
completely invisible to the naked eye, in which state it remains about
five months, and continues increasing during the remainder of its
period. Such is the general course of its phases. But the mean period
above assigned would appear to be subject to a cyclical fluctuation
embracing eighty-eight such periods, and having the effect of gradually
lengthening and shortening alternately those intervals to the extent of
twenty-five days one way and the other. The irregularities in the degree
of brightness attained at the maximum are also periodical.
Such irregularities prepare us for other phenomena of stellar variation
which have hitherto been reduced to no law of periodicity--the phenomena
of temporary stars which have appeared from time to time in different
parts of the heavens blazing forth with extraordinary lustre, and after
remaining awhile, apparently immovable, have died away and left no
trace. In the years 945, 1264, and 1572 brilliant stars appeared in the
region of the heavens between Cepheus and Cassiopeia; and we may suspect
them, with Goodricke, to be one and the same star with a period of 312,
or perhaps 156 years. The appearance of the star of 1572 was so sudden
that Tycho Brahe, a celebrated Dutch astronomer, returning one evening
from his laboratory to his dwellinghouse, was surprised to find a group
of country people gazing at a star which he was sure did not exist half
an hour before. This was the star in question. It was then as bright as
Sirius, and continued to increase till it surpassed Jupiter when
brightest, and was visible at midday. It began to diminish in December
of the same year, and in March 1574 had entirely disappeared.
In 1803 it was announced by Sir William Herschel that there exist
sidereal systems composed of two stars revolving about each other in
regular orbits, and constituting which may be called, to distinguish
them from double stars, which are only optically double, binary stars.
That which since then has been most assiduously watched, and has offered
phenomena of the greatest interest, is _gamma Virginis_. It is a star of
the vulgar third magnitude, and its component individuals are very
nearly equal, and, as it would seem, in some slight degree variable. It
has been known to consist of two stars since the beginning of the
eighteenth century, the distance being then between six and seven
seconds, so that any tolerably good telescope would resolve it. When
observed by Herschel in 1780 it was 5.66 seconds, and continued to
decrease gradually and regularly, till at length, in 1836, the two stars
had approached so closely as to appear perfectly round and single under
the highest magnifying power which could be applied to most excellent
instruments--the great refractor of Pulkowa alone, with a magnifying
power of a thousand, continuing to indicate, by the wedge-shaped form of
the disc of the star, its composite nature.
By estimating the ratio of its length to its breadth, and measuring the
former, M. Struve concludes that at this epoch the distance of the two
stars, centre from centre, might be stated at .22 seconds. From that
time the star again opened, and is now again a perfectly easily
separable star. This very remarkable diminution, and subsequent
increase, of distance has been accompanied by a corresponding and
equally remarkable increase and subsequent diminution of relative
angular motion. Thus in 1783 the apparent angular motion hardly amounted
to half a degree per annum; while in 1830 it had decreased to 5 degrees,
in 1834 to 20 degrees, in 1835 to 40 degrees, and about the middle of
1836 to upwards of 70 degrees per annum, or at the rate of a degree in
five days.
This is in entire conformity with the principles of dynamics, which
establish a necessary connection between the angular velocity and the
distance, as well in the apparent as in the real orbit of one body
revolving about another under the influence of mutual attraction; the
former varying inversely as the square of the latter, in both orbits,
whatever be the curve described and whatever the law of the attractive
force.
It is not with the revolutions of bodies of a planetary or cometary
nature round a solar centre that we are concerned; it is that of sun
round sun--each perhaps, at least in some binary systems, where the
individuals are very remote and their period of revolution very long,
accompanied by its train of planets and their satellites, closely
shrouded from our view by the splendour of their respective suns, and
crowded into a space bearing hardly a greater proportion to the enormous
interval which separates them than the distances of the satellites of
our planets from their primaries bear to their distances from the sun
itself.
A less distinctly characterised subordination would be incompatible with
the stability of their systems and with the planetary nature of their
orbits. Unless close under the protecting wing of their immediate
superior, the sweep of their other sun, in its perihelion passage round
their own, might carry them off or whirl them into orbits utterly
incompatible with conditions necessary for the existence of their
inhabitants.
_IV.--The Nebulæ_
It is to Sir William Herschel that we owe the most complete analysis of
the great variety of those objects which are generally classed as
nebulæ. The great power of his telescopes disclosed the existence of an
immense number of these objects before unknown, and showed them to be
distributed over the heavens not by any means uniformly, but with a
marked preference to a certain district extending over the northern pole
of the galactic circle. In this region, occupying about one-eighth of
the surface of the sphere, one-third of the entire nebulous contents of
the heavens are situated.
The resolvable nebulæ can, of course, only be considered as clusters
either too remote, or consisting of stars intrinsically too faint, to
affect us by their individual light, unless where two or three happen to
be close enough to make a joint impression and give the idea of a point
brighter than the rest. They are almost universally round or oval, their
loose appendages and irregularities of form being, as it were,
extinguished by the distance, and only the general figure of the
condensed parts being discernible. It is under the appearance of objects
of this character that all the greater globular clusters exhibit
themselves in telescopes of insufficient optical power to show them
well.
The first impression which Halley and other early discoverers of
nebulous objects received from their peculiar aspect was that of a
phosphorescent vapour (like the matter of a comet's tail), or a gaseous
and, so to speak, elementary form of luminous sidereal matter. Admitting
the existence of such a medium, Sir W. Herschel was led to speculate on
its gradual subsidence and condensation, by the effect of its own
gravity, into more or less regular spherical or spheroidal forms, denser
(as they must in that case be) towards the centre.
Assuming that in the progress of this subsidence local centres of
condensation subordinate to the general tendency would not be wanting,
he conceived that in this way solid nuclei might arise whose local
gravitation still further condensing, and so absorbing the nebulous
matter each in its immediate neighbourhood, might ultimately become
stars, and the whole nebula finally take on the state of a cluster of
stars.
Among the multitude of nebulæ revealed by his telescope every stage of
this process might be considered as displayed to our eyes, and in every
modification of form to which the general principle might be conceived
to apply. The more or less advanced state of a nebula towards its
segregation into discrete stars, and of these stars themselves towards a
denser state of aggregation round a central nucleus, would thus be in
some sort an indication of age.
ALEXANDER VON HUMBOLDT
Cosmos, a Sketch of the Universe
Frederick Henry Alexander von Humboldt was born in Berlin on
September 14, 1769. In 1788 he made the acquaintance of George
Forster, one of Captain Cook's companions, and geological
excursions made with him were the occasion of his first
publications, a book on the nature of basalt. His work in the
administration of mines in the principalities of Bayreuth and
Anspach furnished materials for a treatise on fossil flora; and in
1827, when he was residing in Paris, he gave to the world his
"Voyage to the Equinoctial Regions of the New Continent," which
embodies the results of his investigations in South America. Two
years later he organised an expedition to Asiatic Russia, charging
himself with all the scientific observations. But his principal
interest lay in the accomplishment of that physical description of
the universe for which all his previous studies had been a
preparation, and which during the years 1845 to 1848 appeared under
the comprehensive title of "Cosmos, or Sketch of a Physical
Description of the Universe." Humboldt died on May 6, 1859.
_I.--The Physical Study of the World_
The natural world may be opposed to the intellectual, or nature to art
taking the latter term in its higher sense as embracing the
manifestations of the intellectual power of man; but these
distinctions--which are indicated in most cultivated languages--must not
be suffered to lead to such a separation of the domain of physics from
that of the intellect as would reduce the physics of the universe to a
mere assemblage of empirical specialities. Science only begins for man
from the moment when his mind lays hold of matter--when he tries to
subject the mass accumulated by experience to rational combinations.
Science is mind applied to nature. The external world only exists for us
so far as we conceive it within ourselves, and as it shapes itself
within us into the form of a contemplation of nature. As intelligence
and language, thought and the signs of thought, are united by secret and
indissoluble links, so, and almost without our being conscious of it,
the external world and our ideas and feelings melt into each other.
"External phenomena are translated," as Hegel expresses it in his
"Philosophy of History," "in our internal representation of them." The
objective world, thought by us, reflected in us, is subjected to the
unchanging, necessary, and all-conditioning forms of our intellectual
being.
The activity of the mind exerts itself on the elements furnished to it
by the perceptions of the senses. Thus, in the youth of nations there
manifests itself in the simplest intuition of natural facts, in the
first efforts made to comprehend them, the germ of the philosophy of
nature.
If the study of physical phenomena be regarded in its bearings not on
the material wants of man, but on his general intellectual progress, its
highest result is found in the knowledge of those mutual relations which
link together the general forces of nature. It is the intuitive and
intimate persuasion of the existence of these relations which at once
enlarges and elevates our views and enhances our enjoyment. Such
extended views are the growth of observation, of meditation, and of the
spirit of the age, which is ever reflected in the operations of the
human mind whatever may be their direction.
From the time when man, in interrogating nature, began to experiment or
to produce phenomena under definite conditions, and to collect and
record the fruits of his experience--so that investigation might no
longer be restricted by the short limits of a single life--the
philosophy of nature laid aside the vague and poetic forms with which
she had at first been clothed, and has adopted a more severe character.
The history of science teaches us how inexact and incomplete
observations have led, through false inductions, to that great number
of erroneous physical views which have been perpetuated as popular
prejudices among all classes of society. Thus, side by side with a solid
and scientific knowledge of phenomena, there has been preserved a system
of pretended results of observation, the more difficult to shake because
it takes no account of any of the facts by which it is overturned.
This empiricism--melancholy inheritance of earlier times--invariably
maintains whatever axioms it has laid down; it is arrogant, as is
everything that is narrow-minded; while true physical philosophy,
founded on science, doubts because it seeks to investigate
thoroughly--distinguishes between that which is certain and that which
is simply probable--and labours incessantly to bring its theories nearer
to perfection by extending the circle of observation. This assemblage of
incomplete dogmas bequeathed from one century to another, this system of
physics made up of popular prejudices, is not only injurious because it
perpetuates error with all the obstinacy of ill-observed facts, but also
because it hinders the understanding from rising to the level of great
views of nature.
Instead of seeking to discover the _mean_ state around which, in the
midst of apparent independence and irregularity, the phenomena really
and invariably oscillate, this false science delights in multiplying
apparent exceptions to the dominion of fixed laws, and seeks, in organic
forms and the phenomena of nature, other marvels than those presented by
internal progressive development, and by regular order and succession.
Ever disinclined to recognise in the present the analogy of the past, it
is always disposed to believe the order of nature suspended by
perturbations, of which it places the seat, as if by chance, sometimes
in the interior of the earth, sometimes in the remote regions of space.
_II.--The Inductive Method_
The generalisation of laws which were first applied to smaller groups of
phenomena advances by successive gradations, and their empire is
extended, and their evidence strengthened, so long as the reasoning
process is directed to really analogous phenomena. Empirical
investigation begins by single perceptions, which are afterwards classed
according to their analogy or dissimilarity. Observation is succeeded at
a much later epoch by experiment, in which phenomena are made to arise
under conditions previously determined on by the experimentalist, guided
by preliminary hypotheses, or a more or less just intuition of the
connection of natural objects and forces.
The results obtained by observation and experiment lead by the path of
induction and analogy to the discovery of empirical laws, and these
successive phases in the application of human intellect have marked
different epochs in the life of nations. It has been by adhering closely
to this inductive path that the great mass of facts has been accumulated
which now forms the solid foundation of the natural sciences.
Two forms of abstraction govern the whole of this class of
knowledge--_viz._, the determination of quantitative relations,
according to number and magnitude; and relations of quality, embracing
the specific properties of heterogeneous matter.
The first of these forms, more accessible to the exercise of thought,
belongs to the domain of mathematics; the other, more difficult to
seize, and apparently more mysterious, to that of chemistry. In order to
submit phenomena to calculation, recourse is had to a hypothetical
construction of matter by a combination of molecules and atoms whose
number, form, position, and polarity determine, modify, and vary the
phenomena.
We are yet very far from the time when a reasonable hope could be
entertained of reducing all that is perceived by our senses to the unity
of a single principle; but the partial solution of the problem--the
tendency towards a general comprehension of the phenomena of the
universe--does not the less continue to be the high and enduring aim of
all natural investigation.
_III.--Distribution of Matter in Space_
A physical cosmography, or picture of the universe, should begin, not
with the earth, but with the regions of space--the distribution of
matter in the universe.
We see matter existing in space partly in the form of rotating and
revolving spheroids, differing greatly in density and magnitude, and
partly in the form of self-luminous vapour dispersed in shining nebulous
spots or patches. The nebulæ present themselves to the eye in the form
of round, or nebulous discs, of small apparent magnitude, either single
or in pairs, which are sometimes connected by a thread of light; when
their diameters are greater their forms vary--some are elongated, others
have several branches, some are fan-shaped, some annular, the ring being
well defined and the interior dark. They are supposed to be undergoing
various and progressive changes of form, as condensation proceeds around
one or more nuclei in conformity with the laws of gravitation. Between
two and three thousand of such unresolvable nebulæ have already been
counted, and their positions determined.
If we leave the consideration of the attenuated vaporous matter of the
immeasurable regions of space, whether existing in a dispersed state as
a cosmical ether without form or limits, or in the shape of nebulæ, and
pass to those portions of the universe which are condensed into solid
spheres or spheroids, we approach a class of phenomena exclusively
designated as stars or as the sidereal universe. Here, too, we find
different degrees of solidity or density in the agglomerated matter.
If we compare the regions of space to one of the island-studded seas of
our planet, we may imagine we see matter distributed in groups, whether
of unresolvable nebulæ of different ages condensed around one or more
nuclei, or in clusters of stars, or in stars scattered singly. Our
cluster of stars, or the island in space to which we belong, forms a
lens-shaped, flattened, and everywhere detached stratum, whose major
axis is estimated at seven or eight hundred, and its minor axis at a
hundred and fifty times, the distance of Sirius. If we assume that the
parallax of Sirius does not exceed that accurately determined for the
brightest stars in Centaur (0.9128 sec.), it will follow that light
traverses one distance of Sirius in three years, while nine years and a
quarter are required for the transmission of the light of the star 61
Cygni, whose considerable proper motion might lead to the inference of
great proximity.
Our cluster of stars is a disc of comparatively small thickness divided,
at about a third its length, into two branches; we are supposed to be
near this division, and nearer to the region of Sirius than to that of
the constellation of the Eagle; almost in the middle of the starry
stratum in the direction of its thickness.
The place of our solar system and the form of the whole lens are
inferred from a kind of scale--_i.e._, from the different number of
stars seen in equal telescopic fields of view. The greater or less
number of stars measures the relative depth of the stratum in different
directions; giving in each case, like the marks on a sounding-line, the
comparative length of visual ray required to reach the bottom; or, more
properly, as above and below do not here apply, the outer limit of the
sidereal stratum.
In the direction of the major axis, where the greater number of stars
are placed behind each other, the remoter ones appear closely crowded
together, and, as it were, united by a milky radiance, and present a
zone or belt projected on the visible celestial vault. This narrow belt
is divided into branches; and its beautiful, but not uniform brightness,
is interrupted by some dark places. As seen by us on the apparent
concave celestial sphere, it deviates only a few degrees from a great
circle, we being near the middle of the entire starry cluster, and
almost in the plane of the Milky Way. If out planetary system were far
outside the cluster, the Milky Way would appear to telescopic vision as
a ring, and at a still greater distance as a resolvable disc-shaped
nebula.
_IV.--On Earth History_
The succession and relative age of different geological formations are
traced partly by the order of superposition of sedimentary strata, of
metamorphic beds, and of conglomerates, but most securely by the
presence of organic remains and their diversities of structure. In the
fossiliferous strata are inhumed the remains of the floras and faunas of
past ages. As we descend from stratum to stratum to study the relations
of superposition, we ascend in the order of time, and new worlds of
animal and vegetable existence present themselves to the view.
In our ignorance of the laws under which new organic forms appear from
time to time upon the surface of the globe, we employ the expression
"new creations" when we desire to refer to the historical phenomena of
the variations which have taken place at intervals in the animals and
plants that have inhabited the basins of the primitive seas and the
uplifted continents.
It has sometimes happened that extinct species have been preserved
entire, even to the minutest details of their tissues and articulations.
In the lower beds of the Secondary Period, the lias of Lyme Regis, a
sepia has been found so wonderfully preserved that a part of the black
fluid with which the animal was provided myriads of years ago to conceal
itself from its enemies has actually served at the present time to draw
its picture. In other cases such traces alone remain as the impression
which the feet of animals have left on wet sand or mud over which they
passed when alive, or the remains of their undigested food (coprolites).
The analytical study of the animal and vegetable kingdoms of the
primitive world has given rise to two distinct branches of science; one
purely morphological, which occupies itself in natural and physiological
descriptions, and in the endeavour to fill up from extinct forms the
chasms which present themselves in the series of existing species; the
other branch, more especially geological considers the relations of the
fossil remains to the superposition and relative age of the sedimentary
beds in which they are found. The first long predominated; and the
superficial manner which then prevailed of comparing fossil and existing
species led to errors of which traces still remain in the strange
denominations which were given to certain natural objects. Writers
attempted to identify all extinct forms with living species, as, in the
sixteenth century, the animals of the New World were confounded by false
analogies with those of the Old.
In studying the relative age of fossils by the order of superposition of
the strata in which they are found, important relations have been
discovered between families and species (the latter always few in
numbers) which have disappeared and those which are still living. All
observations concur in showing that the fossil floras and faunas differ
from the present animal and vegetable forms the more widely in
proportion as the sedimentary beds to which they belong are lower, or
more ancient.
Thus great variations have successively taken place in the general
types of organic life, and these grand phenomena, which were first
pointed out by Cuvier, offer numerical relations which Deshayes and
Lyell have made the object of researches by which they have been
conducted to important results, especially as regards the numerous and
well-preserved fossils of the Tertiary formation. Agassiz, who has
examined 1,700 species of fossil fishes, and who estimates at 8,000 the
number of living species which have been described, or which are
preserved in our collections, affirms that, with the exception of one
small fossil fish peculiar to the argillaceous geodes of Greenland, he
has never met in the Transition, Secondary, or Tertiary strata with any
example of this class specifically identical with any living fish; and
he adds the important remark that even in the lower Tertiary formations
a third of the fossil fishes of the _calcaire grossier_ and of the
London clay belong to extinct families.
We have seen that fishes, which are the oldest vertebrates, first appear
in the Silurian strata, and are found in all the succeeding formations
up to the birds of the Tertiary Period. Reptiles begin in like manner in
the magnesian limestone, and if we now add that the first mammalia are
met with in Oolite, the Stonefield slate; and that the first remains of
birds have been found in the deposits of the cretaceous period, we shall
have indicated the inferior limits, according to our present knowledge,
of the four great divisions of the vertebrates.
In regard to invertebrate animals, we find corals and some shells
associated in the oldest formations with very highly organised
cephalopodes and crustaceans, so that widely different orders of this
part of the animal kingdom appear intermingled; there are, nevertheless,
many isolated groups belonging to the same order in which determinate
laws are discoverable. Whole mountains are sometimes found to consist of
a single species of fossil goniatites, trilobites, or nummulites.
Where different genera are intermingled, there often exists a
systematic relation between the series of organic forms and the
superposition of the formations; and it has been remarked that the
association of certain families and species follows a regular law in the
superimposed strata of which the whole constitutes one formation. It has
been found that the waters in the most distant parts of the globe were
inhabited at the same epochs by testaceous animals corresponding, at
least in generic character, with European fossils.
Strata defined by their fossil contents, or by the fragments of other
rocks which they include, form a geological horizon by which the
geologist may recognise his position, and obtain safe conclusions in
regard to the identity or relative antiquity of formations, the
periodical repetition of certain strata--their parallelism--or their
entire suppression. If we would thus comprehend in its greatest
simplicity the general type of the sedentary formations, we find in
proceeding successively from below upwards: (1) The Transition group,
including the Silurian and Devonian (Old Red Sandstone) systems; (2) the
Lower Trias, comprising mountain limestone, the coal measures, the lower
new red sandstone, and the magnesian limestone; (3) the Upper Trias,
composing the bunter, or variegated sandstone, the muschelkalk, and the
Keuper sandstone; (4) the Oolitic, or Jurassic series, including Lias;
(5) the Cretaceous series; (6) the Tertiary group, as represented in its
three stages by the _calcaire grossier_ and other beds of the Paris
basin, the lignites, or brown coal of Germany, and the sub-Apennine
group of Italy.
To these succeed transported soils (_alluvium_), containing the gigantic
bones of ancient mammalia, such as the mastodons, the dinotherium, and
the megatheroid animals, among which is the mylodon of Owen, an animal
upwards of eleven feet in length, allied to the sloth. Associated with
these extinct species are found the fossil remains of animals still
living: elephants, rhinoceroses, oxen, horses, and deer. Near Bogota, at
an elevation of 8,200 French feet above the level of the sea, there is a
field filled with the bones of mastodon (_Campo de Gigantes_), in which
I have had careful excavations made. The bones found on the table-lands
of Mexico belong to the true elephants of extinct species. The minor
range of the Himalaya, the Sewalik hills, contain, besides numerous
mastodons, the sivatherium and the gigantic land-tortoise
(_Colossochelys_), more than twelve feet in length and six in height, as
well as remains belonging to still existing species of elephants,
rhinoceroses, and giraffes. It is worthy of notice that these fossils
are found in a zone which enjoys the tropical climate supposed to have
prevailed at the period of the mastodons.
_V.--The Permanence of Science_
It has sometimes been regarded as a discouraging consideration that,
while works of literature being fast-rooted in the depths of human
feeling, imagination and reason suffer little from the lapse of time, it
is otherwise with works which treat of subjects dependent on the
progress of experimental knowledge. The improvement of instruments, and
the continued enlargement of the field of observation, render
investigations into natural phenomena and physical laws liable to become
antiquated, to lose their interest, and to cease to be read.
Let none who are deeply penetrated with a true and genuine love of
nature, and with a lively appreciation of the true charm and dignity of
the study of her laws, ever view with discouragement or regret that
which is connected with the enlargement of the boundaries of our
knowledge. Many and important portions of this knowledge, both as
regards the phenomena of the celestial spaces and those belonging to our
own planet, are already based on foundations too firm to be lightly
shaken; although in other portions general laws will doubtless take the
place of those which are more limited in their application, new forces
will be discovered, and substances considered as simple will be
decomposed, while others will become known.
JAMES HUTTON
The Theory of the Earth
James Hutton, the notable Scotch geologist, was born at Edinburgh
on June 3, 1726. In 1743 he was apprenticed to a Writer to the
Signet; but his apprenticeship was of short duration and in the
following year he began to study medicine at Edinburgh University,
and in 1749 graduated as an M.D. Later he determined to study
agriculture, and went, in 1752, to live with a Norfolk farmer to
learn practical farming. He did not devote himself entirely to
agriculture, but gave a considerable amount of his time to chemical
and geological researches. His geological researches culminated in
his great work, "The Theory of the Earth," published at Edinburgh
in 1795. In this work he propounds the theory that the present
continents have been formed at the bottom of the sea by the
precipitation of the detritus of former continents, and that the
precipitate had been hardened by heat and elevated above the sea by
the expansive power of heat. He died on March 26, 1797. Other works
are his "Theory of Rain," "Elements of Agriculture," "Natural
Philosophy," and "Nature of Coal."
_I.--Origin and Consolidation of the Land_
The solid surface of the earth is mainly composed of gravel, of
calcareous, and argillaceous strata. Sand is separated by streams and
currents, gravel is formed by the attrition of stones agitated in water,
and argillaceous strata are deposited by water containing argillaceous
material. Accordingly, the solid earth would seem to have been mainly
produced by water, wind, and tides, and this theory is confirmed by the
discovery that all the masses of marble and limestone are composed of
the calcareous matter of marine bodies. All these materials were, in the
first place, deposited at the bottom of the sea, and we have to
consider, firstly, how they were consolidated; and secondly, how they
came to be dry land, elevated above the sea.
It is plain that consolidation may have been effected either through
the concretion of substances dissolved in water or through fusion by
fire. Consolidation through the concretion of substances dissolved in
the sea is unlikely, for, in the first place, there are strata, such as
siliceous matter, which are insoluble, and which could not therefore
have been in solution; and, in the second place, the appearance of the
strata is contrary to this supposition. Consolidation was probably
effected by heat and fusion. All the substances in the earth may be
rendered fluid by heat, and all the appearances in the earth's crust are
consistent with the consolidation and crystallisation of fused
substances. Not only so, but we find rents and separations and veins in
the strata, such as would naturally occur in strata consolidated by the
cooling of fused masses, and other phenomena pointing to fusion by heat.
We may conclude, then, that all the solid strata of the globe have been
hardened from a state of fusion.
But how were these strata raised up from the bottom of the sea and
transformed into dry land? Even as heat was the consolidating power, so
heat was also probably the elevating power. The power of heat for the
expansion of bodies is, as we know, unlimited, and the expansive power
of heat was certainly competent to raise the strata above the sea. Heat
was certainly competent, and if we examine the crust of the earth we
find evidence that heat was used.
If the strata cemented by the heat of fusion were created by the
expansive power of heat acting from below, we should expect to find
every species of fracture, dislocation, and contortion in those bodies,
and every degree of departure from a horizontal towards a vertical
position. And this is just what we do find. From horizontal, the strata
are frequently found vertical; from continuous, broken, and separated in
every possible direction; and from a plane, bent and doubled. The theory
is confirmed by an examination of the veins and fissures of the earth
which contain matter foreign to the strata they traverse, and evidently
forced into them as a fluid under great pressure. Active volcanoes, and
extinct volcanoes, and the marks everywhere of volcanic action likewise
support the theory of expansion and elevation by heat. A volcano is not
made on purpose to frighten superstitious people into fits of piety and
devotion; it is to be considered as a spiracle of a subterranean
furnace.
Such being the manner of the formation of the crust of the world, can we
form any judgment of its duration and durability? If we could measure
the rate of the attrition of the present continents, we might estimate
the duration of the older continents whose attrition supplied the
material for the present dry land. But as we cannot measure the
wearing-away of the land, we can merely state generally, first, that the
present dry land required an indefinitely long period for its formation;
second, that the previous dry land which supplied material for its
formation required equal time to make; third, that there is at present
land forming at the bottom of the sea which in time will appear above
the surface; fourth, that we find no vestige of a beginning, or of an
end.
Granite has in its own nature no claim to originality, for it is found
to vary greatly in its composition. But, further, it is certain that
granite, or a species of the same kind of stone, is found stratified. It
is the _granit feuilletée_ of M. de Sauffure, and, if I mistake not, is
called _gneiss_ by the Germans. Granite being thus found stratified, the
masses of this stone cannot be allowed to any right of priority over the
schistus, its companion in Alpine countries.
Lack of stratification, then, cannot be considered a proof of primitive
rock. Nor can lack of organized bodies, such as shells, in these rocks,
be considered a proof; for the traces of organized bodies may be
obliterated by the many subsequent operations of the mineral region. In
any case, signs of organized bodies are sometimes found in "primitive"
mountains.
Nor can metallic veins, found plentifully in "primitive" mountains,
prove anything, for mineral veins are found in various strata.
We maintain that _all_ the land was produced from fused substances
elevated from the bottom of the sea. But we do not hold that all parts
of the earth have undergone exactly similar and simultaneous
vicissitudes; and in respect to the changes which various parts of the
land have undergone we may distinguish between primary and secondary
strata. Nothing is more certain than that there have been several
repeated operations of the mineralising power exerted upon the strata in
particular places, and all those mineral operations tend to
consolidation. It is quite possible that "primitive" masses which differ
from the ordinary strata of the globe have been twice subjected to
mineral operations, having been first consolidated and raised as land,
and then submerged in order to be again fused and elevated.
_II.--The Nature of Mineral Coal_
Mineral, or fossil, coal is a species of stratum distinguished by its
inflammable and combustible nature. We find that it differs in respect
to its purity, and also in respect to its inflammability. As is well
known, some coals have almost no earthy ash, some a great deal; and,
again, some coals burn with much smoke and fire, while others burn like
coke. Where, then, did coal come from, and how can we account for its
different species?
A substance proper for the formation of coaly matter is found in
vegetable bodies. But how did it become mixed with earthy matter?
Vegetable bodies may be resolved into bituminous or coaly matter either
by means of fire or by means of water. Both may be used by nature in
the formation of coal.
By the force of subterranean heat vegetable matter may have been charred
at the bottom of the sea, and the oleaginous, bituminous, and fuliginous
substances diffused through the sea as a result of the burning may have
been deposited at the bottom of the sea as coal. Further, the bituminous
matter from the smoke of vegetable substances burned on land would
ultimately be deposited from the atmosphere and settle at the bottom of
the sea.
Many of the rivers contain in solution an immense quantity of
inflammable vegetable substance, and this is carried into the sea, and
precipitated there.
From these two sources, then, the sea gets bituminous material, and this
material, condensed and consolidated by compression and by heat, at the
bottom of the sea, would form a black body of a most uniform structure,
breaking with a polished surface, and burning with more or less smoke or
flame in proportion as it be distilled less or more by subterranean
heat. And such a body exactly represents our purest fossil coal, which
gives the most heat and leaves the least ash.
In some cases the bituminous material in suspension in the sea would be
mixed more or less with argillaceous, calcareous, and other earthy
substances; and these being precipitated along with the bituminous
matter would form layers of impure coal with a considerable amount of
ash.
But there is still a third source of coal. Vegetable bodies macerated in
water, and consolidated by compression, form a body almost
indistinguishable from some species of coal, as is seen in peat
compressed under a great load of earth; and there can be no doubt that
coal sometimes originates in this way, for much fossil coal shows
abundance of vegetable bodies in its composition.
There remains only to consider the change in the disposition of coal
strata. Coal strata, which had been originally in a horizontal position,
are now found sometimes standing erect, even perpendicular. This, also,
is consistent with our theory of the earth. Indeed, there is not a
substance in the mineral kingdom in which the action of subterranean
heat is better shown. These strata are evidently a deposit of
inflammable substances which all come originally from vegetable bodies.
In this stage of their formation they must all contain volatile
oleaginous constituents. But some coal strata contain no volatile
constituents, and the disappearance of the volatile oleaginous
substances must have been produced by distillation, proceeding perhaps
under the restraining force of immense compression.
We cannot doubt that such distillation does take place in the mineral
regions, when we consider that in most places of the earth we find the
evident effects of such distillation in the naphtha and petroleum that
are constantly emitted along with water in certain springs. We have,
therefore, sufficient proof of this operation of distillation.
_III.--The Disintegration and Dissolution of Land_
Whether we examine the mountain or the plain, whether we consider the
disintegration of the rocks or the softer strata of the earth, whether
we regard the shores of seas or the central plains of continents,
whether we contemplate fertile lands or deserts, we find evidence of a
general dissolution and decay of the solid surface of the globe. Every
great river and deep valley gives evidence of the attrition of the land.
The purpose of the dry land is to sustain a system of plants and
animals; and for this purpose a soil is required, and to make a soil the
solid strata must be crumbled down. The earth is nothing more than an
indefinite number of soils and situations suitable for various animals
and plants, and it must consist of both solid rock and tender earth, of
both moist and dry districts; for all these are requisite for the world
we inhabit.
But not only is the solid rock crumbling into soil by the action of air
and water, but the soil gradually progresses towards the sea, and sooner
or later the sea must swallow up the land. Vegetation and masses of
solid rock retard the seaward flow of the soil; but they merely retard,
they cannot wholly prevent. In proportion as the mountains are
diminished, the haugh, or plain, between them grows more wide, and also
on a lower level; but while there is a river running on a plain, and
floods produced in the seasons of rain, there is nothing stable in the
constitution of the surface of the land.
The theory of the earth which I propound is founded upon the great
catastrophes that can happen to the earth. It supposes strata raised
from the bottom of the sea and elevated into mountainous continents.
But, between the catastrophes, it requires nothing further than the
ordinary everyday effects of air and water. Every shower of rain, every
stream, participates in the dissolution of the land, and helps to
transport to the sea the material for future continents.
The prodigious waste of the land we see in places has seemed to some to
require some other explanation; but I maintain that the natural
operations of air and water would suffice in time to produce the effects
observed. It is true that the wastage would be slow; but slow
destruction of rock with gradual formation of soil is just what is
required in the economy of nature. A world sustaining plants and animals
requires continents which endure for more than a day.
If this continent of land, first collected in the sea, is to remain a
habitable earth, and to resist the moving waters of the globe, certain
degrees of solidity or consolidation must be given to that collection of
loose materials; and certain degrees of hardness must be given to
bodies which are soft and incoherent, and consequently so extremely
perishable in the situation in which they are now placed.
But, at the same time that this earth must have solidity and hardness to
resist the sudden changes which its moving fluids would occasion, it
must be made subject to decay and waste upon the surface exposed to the
atmosphere; for such an earth as were made incapable of change, or not
subject to decay, would not afford that fertile soil which is required
in the system of this world--a soil on which depends the growth of
plants and life of animals--the end of its intention.
Now, we find this earth endued precisely with such degree of hardness
and consolidation as qualifies it at the same time to be a fruitful
earth, and to maintain its station with all the permanency compatible
with the nature of things, which are not formed to remain unchangeable.
Thus we have a view of the most perfect wisdom in the contrivance of
that constitution by which the earth is made to answer, in the best
manner possible, the purpose of its intention, that is, to maintain and
perpetuate a system of vegetation, or the various races of useful
plants, or a system of living animals, which are in their turn
subservient to a system still infinitely more important--I mean a system
of intellect. Without fertility in the earth, many races of plants and
animals would soon perish, or be extinct; and with permanency in our
land it were impossible for the various tribes of plants and animals to
be dispersed over the surface of a changing earth. The fact is that
fertility, adequate to the various ends in view, is found in all the
quarters of the world, or in every country of the earth; and the
permanency of our land is such as to make it appear unalterable to
mankind in general and even to impose upon men of science, who have
endeavoured to persuade us that this earth is not to change.
Nothing but supreme power and wisdom could have reconciled those two
opposite ends of intention, so as both to be equally pursued in the
system of nature, and so equally attained as to be imperceptible to
common observation, and at the same time a proper object of the human
understanding.
LAMARCK
Zoological Philosophy
Jean Baptiste de Monet, Chevalier de Lamarck, was born in Picardy,
France, Aug. I, 1744, the cadet of an ancient but impoverished
house. It was his father's desire that he should enter the Church,
but his inclination was for a military life; and having, at the age
of seventeen, joined the French army under De Broglie, he had
within twenty-four hours the good fortune so to distinguish himself
as to win his commission. When the Museum of Natural History was
brought into existence in 1794 he was sufficiently well-known as a
naturalist to be entrusted with the care of the collections of
invertebrates, comprising insects, molluscs, polyps, and worms.
Here he continued to lecture until his death in 1829. Haeckel,
classifying him in the front rank with Goethe and Darwin,
attributes to him "the imperishable glory of having been the first
to raise the theory of descent to the rank of an independent
scientific theory." The form of his theory was announced in 1801,
but was not given in detail to the world until 1809, by the
publication of his "Zoological Philosophy" ("Philosophie
Zoologique"). The Lamarckian theory of the hereditary transmission
of characters acquired by use, disuse, etc., has still a following,
though it is controverted by the schools of Darwin and Weissmann.
Lamarck died on December 18, 1829.
_I.--The Ladder of Life_
If we look backwards down the ladder of animal forms we find a
progressive degradation in the organisation of the creatures comprised;
the organisation of their bodies becomes simpler, the number of their
faculties less. This well-recognised fact throws a light upon the order
in which nature has produced the animals; but it leaves unexplained the
fact that this gradation, though sustained, is irregular. The reason
will become clear if we consider the effects produced by the infinite
diversity of conditions in different parts of the globe upon the
general form, the limbs, and the very organisation of the animals in
question.
It will, in fact, be evident that the state in which we find all animals
is the product, on the one hand, of the growing composition of the
organisation which tends to form a regular gradation; and that, for the
rest, it results from a multitude of circumstances which tend
continually to destroy the regularity of the gradation in the
increasingly composite nature of the organism.
Not that circumstances can effect any modification directly. But changed
circumstances produce changed wants, changed wants changed actions. If
the new wants become constant the animals acquire new habits, which are
no less constant than the wants which gave rise to them. And such new
habits will necessitate the use of one member rather than another, or
even the cessation of the use of a member which has lost its utility.
We will look at some familiar examples of either case. Among vegetables,
which have no actions, and therefore no habits properly so called, great
differences in the development of the parts do none the less arise as a
consequence of changed circumstances; and these differences cause the
development of certain of them, while they attenuate others and cause
them to disappear. But all this is caused by changes in the nutrition of
the plant, in its absorptions and transpirations, in the quantity of
heat and light, of air and moisture, which it habitually receives; and,
lastly, by the superiority which certain of its vital movements may
assert over the others. There may arise between individuals of the same
species, of which some are placed in favourable, others amid
unfavourable, conditions, a difference which by degrees becomes very
notable.
Suppose that circumstances keep certain individuals in an ill-nourished
or languid state. Their internal organisation will at length be
modified, and these individuals will engender offspring which will
perpetuate the modifications thus acquired, and thus will in the end
give place to a race quite distinct from that of which the individual
members come together always under circumstances favourable to their
development.
For instance, if a seed of some meadow flower is carried to dry and
stony ground, where it is exposed to the winds and there germinates, the
consequence will be that the plant and its immediate offspring, being
always ill-nourished, will give rise to a race really different from
that which lives in the field; yet this, none the less, will be its
progenitor. The individuals of this race will be dwarfed; and their
organs, some being increased at the expense of the rest, will show
distinctive proportions. What nature does in a long time we do every day
ourselves. Every botanist knows that the vegetables transplanted to our
gardens out of their native soil undergo such changes as render them at
last unrecognisable.
Consider, again, the varieties among our domestic fowls and pigeons, all
of them brought into existence by being raised in diverse circumstances
and different countries, and such as might be sought in vain in a state
of nature. It is matter of common knowledge that if we raise a bird in a
cage, and keep it there for five or six years, it will be unable to fly
if restored to liberty. There has, indeed, been no change as yet in the
form of its members; but if for a long series of generations individuals
of the same race had been kept caged for a considerable time, there is
no room for doubt that the very form of their limbs would little by
little have undergone notable alteration. Much more would this be the
case if their captivity had been accompanied by a marked change of
climate, and if these individuals had by degrees accustomed themselves
to other sorts of food and to other measures for acquiring it. Such
circumstances, taken constantly together, would have formed insensibly a
new and clearly denned race.
The following example shows, in regard to plants, how the change of
some important circumstance may tend to change the various parts of
these living bodies.
So long as the _ranunculus aquatilis_, the water buttercup, is under
water its leaves are all finely indented, and the divisions are
furnished with capillaries; but as soon as the stalk of the plant
reaches the surface the leaves, which develop in the air, are broadened
out, rounded, and simply lobed. If the plant manages to spring up in a
soil that is merely moist, and not covered with water, the stems will be
short, and none of the leaves will show these indentations and
capillaries. You have then the _ranunculus hederaceus_, which botanists
regard as a distinct species.
Among animals changes take place more slowly, and it is therefore more
difficult to determine their cause. The strongest influence, no doubt,
is that of environment. Places far apart are different, and--which is
too commonly ignored--a given place changes its climate and quality with
time, though so slowly in respect of human life that we attribute to it
perfect stability. Hence it arises that we have not only extreme
changes, but also shadowy ones between the extremes.
Everywhere the order of things changes so gradually that man cannot
observe the change directly, and the animal tribes in every place
preserve their habits for a long time; whence arises the apparent
constancy of what we call species--a constancy which has given birth in
us to the idea that these races are as old as nature.
But the surface of the habitable globe varies in nature, situation, and
climate, in every variety of degrees. The naturalist will perceive that
just in proportion as the environment is notably changed will the
species change their characters.
It must always be recognised:
(1) That every considerable and constant change in the environment of a
race of animals works a real change in their wants.
(2) That every change in their wants necessitates new actions to supply
them, and consequently new habits.
(3) That every new want calling for new actions for its satisfaction
affects the animal in one of two ways. Either it has to make more
frequent use of some particular member, and this will develop the part
and cause it to increase in size; or it must employ new members which
will grow in the animal insensibly in response to the inward yearning to
satisfy these wants. And this I will presently prove from known facts.
How the new wants have been able to attain satisfaction, and how the new
habits have been acquired, it will be easy to see if regard be had to
the two following laws, which observation has always confirmed.
FIRST LAW.--In every animal which has not arrived at the term of
its developments, the more frequent and sustained use of any organ
strengthens, develops, and enlarges that organ, and gives it a
power commensurate with the duration of this employment of it. On
the other hand, constant disuse of such organ weakens it by
degrees, causes it to deteriorate, and progressively diminishes its
faculties, so that in the end it disappears.
SECOND LAW.--All qualities naturally acquired by individuals as the
result of circumstances to which their race is exposed for a
considerable time, or as a consequence of a predominant employment
or the disuse of a certain organ, nature preserves to individual
offspring; provided that the acquired modifications are common to
the two sexes, or, at least, to both parents of the individual
offspring.
Naturalists have observed that the members of animals are adapted to
their use, and thence have concluded hitherto that the formation of the
members has led to their appropriate employment. Now, this is an error.
For observation plainly shows that, on the contrary, the development of
the members has been caused by their need and use; that these have
caused them to come into existence where they were wanting.
But let us examine the facts which bear upon the effects of employment
or disuse of organs resulting from the habits which a race has been
compelled to form.
_II.--The Penalties of Disuse_
Permanent disuse of an organ as a consequence of acquired habits
gradually impoverishes it, and in the end causes it to disappear, or
even annihilates it altogether.
Thus vertebrates, which, in spite of innumerable particular
distinctions, are alike in the plan of their organisation, are generally
armed with teeth. Yet those of them which by circumstances have acquired
the habit of swallowing their prey without mastication have been liable
to leave their teeth undeveloped. Consequently, the teeth have either
remained hidden between the bony plates of the jaws, or have even been,
in the course of time, annihilated.
The whale was supposed to have no teeth at all till M. Geoffrey found
them hidden in the jaws of the foetus. He has also found in birds the
groove in which teeth might be placed, but without any trace of the
teeth themselves. A similar case to that of the whale is the ant-eater
(_nyomecophaga_), which has long given up the practice of mastication.
Eyes in the head are an essential part of the organisation of
vertebrates. Yet the mole, which habitually makes no use of the sense of
sight, has eyes so small that they can hardly be seen; and the aspalax,
whose habits-resemble a mole's, has totally lost its sight, and shows
but vestiges of eyes. So also the proteus, which inhabits dark caves
under water.
In such cases, since the animals in question belong to a type of which
eyes are an essential part, it is clear that the impoverishment, and
even the total disappearance, of these organs are the results of long
continued disuse.
With hearing, the case is otherwise. Sound traverses everything.
Therefore, wherever an animal dwells it may exercise this faculty. And
so no vertebrate lacks it, and we never find it re-appearing in any of
the lower ranges. Sight disappears, re-appears, and disappears again,
according as circumstances deny or permit its exercise.
Four legs attached to its skeleton are part of the reptile type; and
serpents, particularly as between them and the fishes come the
batrachians--frogs, etc.--ought to have four legs.
But serpents, having acquired the habit of gliding along the ground, and
concealing themselves amid the grass, their bodies, as a consequence of
constantly repeated efforts to lengthen themselves out in order to pass
through narrow passages, have acquired considerable length of body which
is out of all proportion to their breadth.
Now, feet would have been useless to these animals, and consequently
would have remained unemployed; for long legs would have interfered with
their desire to go on their bellies; and short legs, being limited in
number to four, would have been incapable of moving their bodies. Thus
total disuse among these races of animals has caused the parts which
have fallen into disuse totally to disappear.
Many insects, which by their order and genus should have wings, lack
them more or less completely for similar reasons.
_III.--The Advantages of Use_
The frequent use of an organ, if constant and habitual, increases its
powers, develops it, and makes it acquire dimensions and potency such
as are not found among animals which use it less.
Of this principle, the web-feet of some birds, the long legs and neck of
the stork, are examples. Similarly, the elongated tongue of the
ant-eater, and those of lizards and serpents.
Such wants, and the sustained efforts to satisfy them, have also
resulted in the displacement of organs. Fishes which swim habitually in
great masses of water, since they need to see right and left of them,
have the eyes one upon either side of the head. Their bodies, more or
less flat, according to species, have their edges perpendicular to the
plane of the water; and their eyes are so placed as to be one on either
side of the flattened body. But those whose habits bring them constantly
to the banks, especially sloping banks, have been obliged to lie over
upon the flattened surface in order to approach more nearly. In this
position, in which more light falls on the upper than on the under
surface, and their attention is more particularly fixed upon what is
going on above than on what is going on below them, this want has forced
one of the eyes to undergo a kind of displacement, and to keep the
strange position which it occupies in the head of a sole or a turbot.
The situation is not symmetrical because the mutation is not complete.
In the case of the skate, however, it is complete; for in these fish the
transverse flattening of the body is quite horizontal, no less than that
of the head. And so the eyes of a skate are not only placed both of them
on the upper surface, but have become symmetrical.
Serpents need principally to see things above them, and, in response to
this need, the eyes are placed so high up at the sides of the head that
they can see easily what is above them on either side, while they can
see in front of them but a very little distance. To compensate for this,
the tongue, with which they test bodies in their line of march, has been
rendered by this habit thin, long, and very contractile, and even, in
most species, has been split so as to be able to test more than one
object at a time. The same custom has resulted similarly in the
formation of an opening at the end of the muzzle by which the tongue may
be protruded without any necessity for the opening of the jaws.
The effect of use is curiously illustrated in the form and figure of the
giraffe. This animal, the largest of mammals, is found in the interior
of Africa, where the ground is scorched and destitute of grass, and has
to browse on the foliage of trees. From the continual stretching thus
necessitated over a great space of time in all the individuals of the
race, it has resulted that the fore legs have become longer than the
hind legs, and that the neck has become so elongated that the giraffe,
without standing on its hind legs, can raise its head to a height of
nearly twenty feet. Observation of all animals will furnish similar
examples.
None, perhaps, is more striking than that of the kangaroo. This animal,
which carries its young in an abdominal pouch, has acquired the habit of
carrying itself upright upon its hind legs and tail, and of moving from
place to place in a series of leaps, during which, in order not to hurt
its little ones, it preserves its upright posture. Observe the result.
(1) Its front limbs, which it uses very little, resting on them only in
the instant during which it quits its erect posture, have never acquired
a development in proportion to the other parts; they have remained thin,
little, and weak.
(2) The hind legs, almost continually in action, whether to bear the
weight of the whole body or to execute its leaps, have, on the contrary,
obtained a considerable development; they are very big and very strong.
(3) Finally, the tail, which we observe to be actively employed, both to
support the animal's weight and to execute its principal movements, has
acquired at its base a thickness and a strength that are extremely
remarkable.
When the will determines an animal to a certain action, the organs
concerned are forthwith stimulated by a flow of subtle fluids, which are
the determining cause of organic changes and developments. And
multiplied repetitions of such acts strengthen, extend, and even call
into being the organs necessary to them. Now, every change in an organ
which has been acquired by habitual use sufficient to originate it is
reproduced in the offspring if it is common to both the individuals
which have come together for the reproduction of their species. In the
end, this change is propagated and passes to all the individuals which
come after and are submitted to the same conditions, without its being
necessary that they should acquire it in the original manner.
For the rest, in the union of disparate couples, the disparity is
necessarily opposed to the constant propagation of such qualities and
outward forms. This is why man, who is exposed to such diversity of
conditions, does not preserve and propagate the qualities or the
accidental defects which he has been in the way of acquiring. Such
peculiarities will be produced only in case two individuals who share
them unite; these will produce offspring bearing similar
characteristics, and, if successive generations restrict themselves to
similar unions, a distinct race will then be formed. But perpetual
intermixture will cause all characters acquired through particular
circumstances to disappear. If it were not for the distances which
separate the races of men, such intermixture would quickly obliterate
all national distinctions.
_IV.--The Conclusion_
Here, then, is the conclusion to which we have come. It is a fact that
every genus and species of animal has its characteristic habits combined
with an organisation perfectly in harmony with them. From the
consideration of this fact one of two conclusions must follow, and that
though neither of them can be proved.
(1) The conclusion admitted hitherto--that nature (or its Author) in
creating the animals has foreseen all the possible sets of circumstances
in which they would have to live, has given to each species a constant
organisation, and has shaped its parts in a determined and invariable
way so that every species is compelled to live in the districts and the
climates where it is actually formed, and to keep the habits by which it
is actually known.
(2) My own conclusion--that nature has produced in succession all the
animal species, beginning with the more imperfect, or the simpler, and
ending with the more perfect; that in so doing it has gradually
complicated their organisation; and that of these animals, dispersed
over the habitable globe, every species has acquired, under the
influence of the circumstances amid which it is found, the habits and
modifications of form which we associate with it.
To prove that the second of these hypotheses is unfounded, it will be
necessary, first, to prove that the surface of the globe never varies in
character, in exposure, situation, whether elevated or sheltered,
climate, etc.; and, secondly, to prove that no part of the animal world
undergoes, even in the course of long periods of time, any modification
through change of circumstances, or as a consequence of a changed manner
of life and action.
Now, a single fact which establishes that an animal, after a long period
of domestication, differs from the wild stock from which it derives, and
that among the various domesticated members of a species may be found
differences no less marked between individuals which, have been
subjected to one use and those which have been subjected to another,
makes it certain that the former conclusion is not consistent with the
laws of nature, and that the second is.
Everything, therefore, concurs to prove my assertion, to wit--that it is
not form, whether of the body or of the parts, which gives rise to the
habits of animals and their manner of life; but that, on the contrary,
in the habits, the manner of living, and all the other circumstances of
environment, we have those things which in the course of time have built
up animal bodies with all their members. With new forms new faculties
have been acquired, and little by little nature has come to shape
animals and all living things in their present forms.
JOHANN LAVATER
Physiognomical Fragments
Johann Caspar Lavater, the Swiss theologian, poet, and
physiognomist, was born at Zürich on November 15, 1741. He began
his public life at the age of twenty-one as a political reformer.
Five years later he appeared as a poet, and published a volume of
poetry which was very favourably received. During the next five
years he produced a religious work, which was considered heretical,
although its mystic, religious enthusiasm appealed to a
considerable audience. His fame, however, rests neither on his
poetry nor on his theology, but on his physiognomical studies,
published in four volumes between 1775-78 under the title
"Physiognomical Fragments for the Advancement of Human Knowledge
and Human Life" ("Physiognomische Fragmente zur Beförderung des
Menschenkenntniss und Menschenliebe"). The book is diffuse and
inconsequent, but it contains many shrewd observations with respect
to physiognomy and has had no little influence on popular opinion
in this matter. Lavater died on January 2, 1801.
_I.--The Truth of Physiognomy_
There can be no doubt of the truth of physiognomy. All countenances, all
forms, all created beings, are not only different from each other in
their classes, races, kinds, but are also individually distinct. It is
indisputable that all men estimate all things whatever by their external
temporary superficies--that is to say, by their physiognomy. Is not all
nature physiognomy, superficies and contents, body and spirit, external
effect and internal power? There is not a man who does not judge of all
things that pass through his hands by their physiognomy--there is not a
man who does not more or less, the first time he is in company with a
stranger, observe, estimate, compare, judge him according to
appearances. When each apple, each apricot, has a physiognomy peculiar
to itself, shall man, the lord of the earth, have none?
Man is the most perfect of all earthly creatures. In no other creature
are so wonderfully united the animal, the intellectual, and the moral.
And man's organisation peculiarly distinguishes him from all other
beings, and shows him to be infinitely superior to all those other
visible organisms by which he is surrounded. His head, especially his
face, convinces the accurate observer, who is capable of investigating
truth, of the greatness and superiority of his intellectual qualities.
The eye, the expression, the cheeks, the mouth, the forehead, whether
considered in a state of entire rest, or during their innumerable
varieties of motion--in fine, whatever is understood by physiognomy--are
the most expressive, the most convincing picture of interior sensations,
desires, passions, will, and of all those properties which so much exalt
moral above animal life.
Although the physiological, intellectual, and moral are united in man,
yet it is plain that each of these has its peculiar station where it
more especially unfolds itself and acts.
It is, beyond contradiction, evident that, though physiological or
animal life displays itself through all the body, and especially through
all the animal parts, yet it acts more conspicuously in the arm, from
the shoulder to the ends of the fingers.
It is not less evident that intellectual life, or the powers of the
understanding and the mind, make themselves most apparent in the
circumference and form of the solid parts of the head, especially the
forehead; though they will discover themselves to the attentive and
accurate eye in every part and point of the human body, by the
congeniality and harmony of the various parts. Is there any occasion to
prove that the power of thinking resides not in the foot, nor in the
hand, nor in the back, but in the head and its internal parts?
The moral life of man particularly reveals itself in the lines, marks,
and transitions of the countenance. His moral powers and desires, his
irritability, sympathy, and antipathy, his facility of attracting or
repelling the objects that surround him--these are all summed up in, and
painted upon, his countenance when at rest.
Not only do mental and moral traits evince themselves in the
physiognomy, but also health and sickness; and I believe that by
repeatedly examining the firm parts and outlines of the bodies and
countenances of the sick, disease might be diagnosed, and even that
liability to disease might be predicted in particular cases.
The same vital powers that make the heart beat and the fingers move,
roof the skull and arch the finger-nails. From the head to the back,
from the shoulder to the arm, from the arm to the hand, from the hand to
the finger, each depends on the other, and all on a determinate effect
of a determinate power. Through all nature each determinate power is
productive of only such and such determinate effects. The finger of one
body is not adapted to the hand of another body. The blood in the
extremity of the finger has the character of the blood in the heart. The
same congeniality is found in the nerves and in the bones. One spirit
lives in all. Each member of the body, too, is in proportion to the
whole of which it is a part. As from the length of the smallest member,
the smallest joint of the finger, the proportion of the whole, the
length and breadth of the body may be found; so also may the form of the
whole be found from the form of each single part. When the head is long,
all is long; when the head is round, all is round; when the head is
square, all is square.
One form, one mind, one root appertain to all. Each organised body is so
much a whole that, without discord, destruction, or deformity, nothing
can be added or subtracted. Those, therefore, who maintain that
conclusion cannot be drawn from a part to the whole labour under error,
failing to comprehend the harmony of nature.
_II.--Physiognomy and the Features_
The Forehead. The form, height, arching, proportion, obliquity, and
position of the skull, or bone of the forehead, show the propensity of
thought, power of thought, and sensibility of man. The position, colour,
wrinkles, tension of the skin of the forehead, show the passions and
present state of the mind. The bones indicate the power, the skin the
application of power.
I consider the outline and position of the forehead to be the most
important feature in physiognomy. We may divide foreheads into three
principal classes--the retreating, the perpendicular, and the
projecting, and each of these classes has a multitude of variations.
A few facts with respect to foreheads may now be given.
The higher the forehead, the more comprehension and the less activity.
The more compressed, short, and firm the forehead, the more compression
and firmness, and the less volatility in the man.
The more curved and cornerless the outline, the more tender and flexible
the character; and the more rectilinear, the more pertinacious and
severe the character.
Perfect perpendicularity implies lack of understanding, but gently
arched at top, capacity for cold, tranquil, profound thought.
A projecting forehead indicates imbecility, immaturity, weakness,
stupidity.
A retreating forehead, in general, denotes superior imagination, wit,
acuteness.
A forehead round and prominent above, straight below, and, on the whole,
perpendicular, shows much understanding, life, sensibility, ardour.
An oblique, rectilinear forehead is ardent and vigorous.
Arched foreheads appear properly to be feminine.
A forehead neither too perpendicular nor too retreating, but a happy
mean, indicates the post-perfect character of wisdom.
I might also state it as an axiom that straight lines considered as
such, and curves considered as such, are related as power and weakness,
obstinacy and flexibility, understanding and sensation.
I have seen no man with sharp, projecting eyebones who was not inclined
to vigorous thinking and wise planning.
Yet, even lacking sharpness, a head may be excellent if the forehead
sink like a perpendicular wall upon horizontal eyebrows, and be greatly
rounded towards the temples.
Perpendicular foreheads, projecting so as not to rest immediately upon
the nose, and small, wrinkled, short, and shining, indicate little
imagination, little understanding, little sensation.
Foreheads with many angular, knotty protuberances denote perseverance
and much vigorous, firm, harsh, oppressive, ardent activity.
It is a sure sign of a clear, sound understanding and a good temperament
when the profile of the forehead has two proportionate arches, the lower
of which projects.
Eyebones with well-marked, firm arches I never saw but in noble and
great men.
Square foreheads with extensive temples and firm eyebones show
circumspection and steadiness of character.
Perpendicular wrinkles, if natural, denote application and power.
Horizontal wrinkles and those broken in the middle or at the extremities
generally denote negligence or want of power.
Perpendicular, deep indentings in the forehead between the eyebrows, I
never met save in men of sound understanding and free and noble minds,
unless there were some positively contradictory feature.
A blue frontal vein, in the form of a Y, when in an open, smooth,
well-arched forehead, I have only found in men of extraordinary talents
and of ardent and generous character.
The following are the traits of a perfectly beautiful, intelligent, and
noble forehead.
In length it must equal the nose, or the under part of the face. In
breadth it must be either oval at the top-like the foreheads of most of
the great men of England--or nearly square. It must be free from
unevenness and wrinkles, yet be able to wrinkle when deep in thought,
afflicted by pain, or moved by indignation. It must retreat above and
project beneath. The eyebones must be simple, horizontal, and, if seen
from above, must present a simple curve. There should be a small cavity
in the centre, from above to below, and traversing the forehead so as to
separate it into four divisions perceptible in a clear descending light.
The skin must be more clear on the forehead than in other parts of the
countenance.
Foreheads short, wrinkled, and knotty, are incapable of durable
friendship.
Be not discouraged though a friend, an enemy, a child, or a brother
transgress, for so long as he have a good, well-proportioned, open
forehead there is still hope of improvement.
THE EYES AND EYEBROWS. Blue eyes are generally more indicative of
weakness and effeminacy than brown or black. Certainly there are many
powerful men with blue eyes, but I find more strength, manhood, thought
with brown.
Choleric men have eyes of every colour, but rather brown or greenish
than blue. A propensity to green is an almost decisive token of ardour,
fire, and courage.
Wide open eyes, with the white visible, I have often observed both in
the timid and phlegmatic, and in the courageous and rash.
Meeting eyebrows were supposed to be the mark of craft, but I do not
believe them to have this significance. Angular, strong, interrupted
eyebrows denote fire and productive activity. The nearer the eyebrows to
the eyes, the more earnest, deep, and firm the character. Eyebrows
remote from each other denote warm, open, quick sensations. White
eyebrows signify weakness; and dark brown, firmness. The motion of the
eyebrows contains numerous expressions, especially of ignoble passions.
THE NOSE. I have generally considered the nose the foundation or
abutment of the brain, for upon this the whole power of the arch of the
forehead rests. A beautiful nose will never be found accompanying an
ugly countenance. An ugly person may have fine eyes, but not a handsome
nose.
I have never seen a nose with a broad back, whether arched or
rectilinear, that did not belong to an extraordinary man. Such a nose
was possessed by Swift, Cæsar Borgia, Titian, etc. Small nostrils are
usually an indubitable sign of unenterprising timidity. The open,
breathing nostril is as certain a token of sensibility.
THE MOUTH AND LIPS. The contents of the mind are communicated to the
mouth. How full of character is the mouth! As are the lips, so is the
character. Firm lips, firm character; weak lips, weak character.
Well-defined, large, and proportionate lips, the middle line of which is
equally serpentine on both sides, and easy to be drawn, are never seen
in a bad, mean, common, false, vicious countenance. A lipless mouth,
resembling a single line, denotes coldness, industry, a love of order,
precision, house-wifery, and, if it be drawn upwards at the two ends,
affectation, pretension, vanity, malice. Very fleshy lips have always to
contend with sensuality and indolence. Calm lips, well closed, without
constraint, and well delineated, certainly betoken consideration,
discretion, and firmness. Openness of mouth speaks complaint, and
closeness, endurance.
THE CHIN. From numerous experiments, I am convinced that the projecting
chin ever denotes something positive, and the retreating something
negative. The presence or absence of strength in man is often signified
by the chin.
I have never seen sharp indentings in the middle of the chin save in men
of cool understanding, unless when something evidently contradictory
appeared in the countenance. The soft, fat, double chin generally points
out the epicure; and the angular chin is seldom found save in discreet,
well-disposed, firm men. Flatness of chin speaks the cold and dry;
smallness, fear; and roundness, with a dimple, benevolence.
SKULLS. HOW much may the anatomist see in the mere skull of man! How
much more the physiognomist! And how much more still the anatomist who
is a physiognomist! If shown the bald head of Cæsar, as painted by
Rubens or Titian or Michael Angelo, what man would fail to notice the
rocky capacity which characterises it, and to realise that more ardour
and energy must be expected than from a smooth, round, flat head? How
characteristic is the skull of Charles XII.! How different from the
skull of his biographer Voltaire! Compare the skull of Judas with the
skull of Christ, after Holbein, and I doubt whether anyone would fail to
guess which is the skull of the wicked betrayer and which the skull of
the innocent betrayed. And who is unacquainted with the statement in
Herodotus that it was possible on the field of battle to distinguish the
skulls of the effeminate Medes from the skulls of the manly Persians?
Each nation, indeed, has its own characteristic skull.
_III.--Nation, Sex, and Family_
NATIONAL PHYSIOGNOMY. It is undeniable that there is a national
physiognomy as well as national character. Compare a negro and an
Englishman, a native of Lapland and an Italian, a Frenchman and an
inhabitant of Tierra del Fuego. Examine their forms, countenances,
characters, and minds. This difference will be easily seen, though it
will sometimes be very difficult to describe it scientifically.
The following infinitely little is what I have hitherto observed in the
foreigners with whom I have conversed.
I am least able to characterise the French, They have no traits so bold
as the English, nor so minute as the Germans. I know them chiefly by
their teeth and their laugh. The Italians I discover by the nose, small
eyes, and projecting chin. The English by their foreheads and eyebrows.
The Dutch by the rotundity of their heads and the weakness of the hair.
The Germans by the angles and wrinkles round the eyes and in the cheeks.
The Russians by the snub nose and their light-coloured or black hair.
I shall now say a word concerning Englishmen in particular. Englishmen
have the shortest and best-arched foreheads--that is to say, they are
arched only upwards, and, towards the eyebrows, either gently recline or
are rectilinear. They seldom have pointed, usually round, full noses.
Their lips are usually large, well defined, beautifully curved. Their
chins are round and full. The outline of their faces is in general
large, and they never have those numerous angles and wrinkles by which
the Germans are so especially distinguished. Their complexion is fairer
than that of the Germans.
All Englishwomen whom I have known personally, or by portrait, appear to
be composed of marrow and nerve. They are inclined to be tall, slender,
soft, and as distant from all that is harsh, rigorous, or stubborn as
heaven is from earth.
The Swiss have generally no common physiognomy or national character,
the aspect of fidelity excepted. They are as different from each other
as nations the most remote.
THE PHYSIOGNOMICAL RELATION OF THE SEXES. Generally speaking, how much
more pure, tender, delicate, irritable, affectionate, flexible, and
patient is woman than man. The primary matter of which woman is
constituted appears to account for this difference. All her organs are
tender, yielding, easily wounded, sensible, and receptive; they are made
for maternity and affection. Among a thousand women, there is hardly one
without these feminine characteristics.
This tenderness and sensibility, the light texture of their fibres and
organs, render them easy to tempt and to subdue, and yet their charms
are more potent than the strength of man. Truly sensible of purity,
beauty and symmetry, woman does not always take time to reflect on
spiritual life, spiritual death, spiritual corruption.
The woman does not think profoundly; profound thought is the prerogative
of the man; but women feel more. They rule with tender looks, tears, and
sighs, but not with passion and threats, unless they are monstrosities.
They are capable of the sweetest sensibility, the deepest emotion, the
utmost humility, and ardent enthusiasm. In their faces are signs of
sanctity which every man honours.
Owing to their extreme sensibility and their incapacity for accurate
inquiry and firm decision, they may easily become fanatics.
The love of women, strong as it is, is very changeable; but their hatred
is almost incurable, and is only to be overcome by persistent and artful
flattery. Men usually see things as a whole, whereas women take more
interest in details.
Women have less physical courage than men. Man hears the bursting
thunders, views the destructive bolt with serene aspect, and stands
erect amid the fearful majesty of the torrent. But woman trembles at the
lightning and thunder, and seeks refuge in the arms of man.
Woman is formed for pity and religion; and a woman without religion is
monstrous; and a woman who is a freethinker is more disgusting than a
woman with a beard.
Woman is not a foundation on which to build. She is the gold, silver,
precious stones, wood, hay, stubble--the materials for building on the
male foundation. She is the leaven, or, more expressly, she is oil to
the vinegar of man. Man singly is but half a man, only half human--a
king without a kingdom. Woman must rest upon the man, and man can be
what he ought to be only in conjunction with the woman.
Some of the principal physiognomical contrasts may be summarised here.
Man is the most firm; woman the most flexible.
Man is the straightest; woman the most bending.
Man stands steadfast; woman gently retreats.
Man surveys and observes; woman glances and feels.
Man is serious; woman is gay.
Man is the tallest and broadest; woman the smallest and weakest.
Man is rough and hard; woman is smooth and soft.
Man is brown; woman is fair.
The hair of the man is strong and short; the hair of woman is pliant and
long.
Man has most straight lines; woman most curved.
The countenance of man, taken in profile, is not so often perpendicular
as that of woman.
FAMILY PHYSIOGNOMY. The resemblance between parents and children is very
commonly remarkable. Family physiognomical resemblance is as undeniable
as national physiognomical resemblance. To doubt this is to doubt what
is self-evident.
When children, as they increase in years, visibly increase in their
physical resemblance to their parents, we cannot doubt that resemblance
in character also increases. Howsoever much the character of children
may seem to differ from that of their parents, yet this difference will
be found to be due to great difference in external circumstances.
JUSTUS VON LIEBIG
Animal Chemistry
Baron Freiherr Justus von Liebig, one of the most illustrious
chemists of his age, was born on May 12, 1803, at Darmstadt,
Germany, the son of a drysalter. It was in his father's business
that his interest in chemistry first awoke, and at fifteen he
became an apothecary's assistant. Subsequently, he went to
Erlangen, where he took his doctorate in 1822; and afterwards, in
Paris, was admitted to the laboratory of Gay-Lussac as a private
pupil. In 1824 he was appointed a teacher of chemistry in the
University of Giessen in his native state. Here he lived for
twenty-eight years a quiet life of incessant industry, while his
fame spread throughout Europe. In 1845 he was raised to the
hereditary rank of baron, and seven years later was appointed by
the Bavarian government to the professorship of chemistry in the
University of Munich. Here he died on April 18, 1873. The treatise
on "Animal Chemistry, or Organic Chemistry in its Relations to
Physiology and Pathology," published in 1842, sums up the results
of Liebig's investigations into the immediate products of animal
life. He was the first to demonstrate that the only source of
animal heat is that produced by the oxidation of the tissues.
_I.--Chemical Needs of Life_
Animals, unlike plants, require highly organised atoms for nutriment;
they can subsist only upon parts of an organism. All parts of the animal
body are produced from the fluid circulating within its organism. A
destruction of the animal body is constantly proceeding, every motion is
the result of a transformation of its structure; every thought, every
sensation is accompanied by a change in the composition of the substance
of the brain. Food is applied either in the increase of the mass of a
structure (nutrition) or in the replacement of a structure wasted
(reproduction).
Equally important is the continual absorption of oxygen from the
atmosphere. All vital activity results from the mutual action of the
oxygen of the atmosphere and the elements of food. According to
Lavoisier, an adult man takes into his system every year 827 lb. of
oxygen, and yet he does not increase in weight. What, then, becomes of
this oxygen?--for no part of it is again expired as oxygen. The carbon
and hydrogen of certain parts of the body have entered into combination
with the oxygen introduced through the lungs and through the skin, and
have been given out in the form of carbonic acid and the vapour of
water.
Now, an adult inspires 32-1/2 oz. of oxygen daily; this will convert the
carbon of 24 lb. of blood (80 per cent. water) into carbonic acid. He
must, therefore, take as much nutriment as will supply the daily loss.
And, in fact, it is found that he does so; for the average amount of
carbon in the daily food of an adult man is 14 oz., which requires 37
oz. of oxygen for its conversion into carbonic acid. The amount of food
necessary for the support of the animal body must be in direct ratio to
the quantity of oxygen taken into the system. A bird deprived of food
dies on the third day; while a serpent, which inspires a mere trace of
oxygen, can live without food for three months. The number of
respirations is less in a state of rest than in exercise, and the amount
of food necessary in both conditions must vary also.
The capacity of the chest being a constant quantity, we inspire the same
volume of air whether at the pole or at the equator; but the weight of
air, and consequently of oxygen, varies with the temperature. Thus, an
adult man takes into the system daily 46,000 cubic inches of oxygen,
which, if the temperature be 77° F., weighs 32-1/2 oz., but when the
temperature sinks to freezing-point will weigh 35 oz. It is obvious,
also, that in an equal number of respirations we consume more oxygen at
the level of the sea than on a mountain. The quantity of oxygen inspired
and carbonic acid expired must, therefore, vary with the height of the
barometer. In our climate the difference between summer and winter in
the carbon expired, and therefore necessary for food, is as much as
one-eighth.
_II.--The Cause of Animal Heat_
Now, the mutual action between the elements of food and the oxygen of
the air is the source of animal heat.
This heat is wholly due to the combustion of the carbon and hydrogen in
the food consumed. Animal heat exists only in those parts of the body
through which arterial blood (and with it oxygen in solution)
circulates; hair, wool, or feathers, do not possess an elevated
temperature.
As animal heat depends upon respired oxygen, it will vary according to
the respiratory apparatus of the animal. Thus the temperature of a child
is 102° F., while that of an adult is 99-1/2° F. That of birds is higher
than that of quadrupeds or that of fishes or amphibia, whose proper
temperature is 3° F higher than the medium in which they live. All
animals, strictly speaking, are warm-blooded; but in those only which
possess lungs is their temperature quite independent of the surrounding
medium. The temperature of the human body is the same in the torrid as
in the frigid zone; but the colder the surrounding medium the greater
the quantity of fuel necessary to maintain its heat.
The human body may be aptly compared to the furnace of a laboratory
destined to effect certain operations. It signifies nothing what
intermediate forms the food, or fuel, of the furnace may assume; it is
finally converted into carbonic acid and water. But in order to sustain
a fixed temperature in the furnace we must vary the quantity of fuel
according to the external temperature.
In the animal body the food is the fuel; with a proper supply of oxygen
we obtain the heat given out during its oxidation or combustion. In
winter, when we take exercise in a cold atmosphere, and when
consequently the amount of inspired oxygen increases, the necessity for
food containing carbon and hydrogen increases in the same ratio; and by
gratifying the appetite thus excited, we obtain the most efficient
protection against the most piercing cold. A starving man is soon frozen
to death; and everyone knows that the animals of prey in the Arctic
regions far exceed in voracity those in the torrid zone. In cold and
temperate climates, the air, which incessantly strives to consume the
body, urges man to laborious efforts in order to furnish the means of
resistance to its action, while in hot climates the necessity of labour
to provide food is far less urgent.
Our clothing is merely the equivalent for a certain amount of food.
The more warmly we are clothed the less food we require. If in hunting
or fishing we were exposed to the same degree of cold as the Samoyedes
we could with ease consume ten pounds of flesh, and perhaps half a dozen
tallow candles into the bargain. The macaroni of the Italian, and the
train oil of the Greenlander and the Russian, are fitted to administer
to their comfort in the climate in which they have been born.
The whole process of respiration appears most clearly developed in the
case of a man exposed to starvation. Currie mentions the case of an
individual who was unable to swallow, and whose body lost 100 lb. in one
month. The more fat an animal contains the longer will it be able to
exist without food, for the fat will be consumed before the oxygen of
the air acts upon the other parts of the body.
There are various causes by which force or motion may be produced. But
in the animal body we recognise as the ultimate cause of all force only
one cause, the chemical action which the elements of the food and the
oxygen of the air mutually exercise on each other. The only known
ultimate cause of vital force, either in animals or in plants, is a
chemical process. If this be prevented, the phenomena of life do not
manifest themselves, or they cease to be recognisable by our senses. If
the chemical action be impeded, the vital phenomena must take new forms.
The heat evolved by the combustion of carbon in the body is sufficient
to account for all the phenomena of animal heat. The 14 oz. of carbon
which in an adult are daily converted into carbonic acid disengage a
quantity of heat which would convert 24 lb. of water, at the temperature
of the body, into vapour. And if we assume that the quantity of water
vaporised through the skin and lungs amounts to 3 lb., then we have
still a large quantity of heat to sustain the temperature of the body.
_III.--The Chemistry of Blood-Making_
Physiologists conceive that the various organs in the body have
originally been formed from blood. If this be admitted, it is obvious
that those substances alone can be considered nutritious that are
capable of being transformed into blood.
When blood is allowed to stand, it coagulates and separates into a
watery fluid called serum, and into the clot, which consists principally
of fibrine. These two bodies contain, in all, seven elements, among
which sulphur, phosphorus, and nitrogen are found; they contain also the
earth of bones. The serum holds in solution common salt and other salts
of potash and soda, of which the acids are carbonic, phosphoric, and
sulphuric acids. Serum, when heated, coagulates into a white mass called
albumen. This substance, along with the fibrine and a red colouring
matter in which iron is a constituent, constitute the globules of blood.
Analysis has shown that fibrine and albumen are perfectly identical in
chemical composition. They may be mutually converted into each other. In
the process of nutrition both may be converted into muscular fibre, and
muscular fibre is capable of being reconverted into blood.
All parts of the animal body which form parts of organs contain
nitrogen. The principal ingredients of blood contain 17 per cent. of
nitrogen, and there is no part of an active organ that contains less
than 17 per cent. of this element.
The nutritive process is simplest in the case of the carnivora, for
their nutriment is chemically identical in composition with their own
tissues. The digestive apparatus of graminivorous animals is less
simple, and their food contains very little nitrogen. From what
constituents of vegetables is their blood produced?
Chemical researches have shown that all such parts of vegetables as can
afford nutriment to animals contain certain constituents which are rich
in nitrogen; and experience proves that animals require for their
nutrition less of these parts of plants in proportion as they abound in
the nitrogenised constituents. These important products are specially
abundant in the seeds of the different kinds of grain, and of peas,
beans, and lentils. They exist, however, in all plants, without
exception, and in every part of plants in larger or smaller quantity.
The nitrogenised compounds of vegetables are called vegetable fibrine,
vegetable albumen, and vegetable casein. All other nitrogenised
compounds occurring in plants are either rejected by animals or else
they occur in the food in such very small proportion that they cannot
possibly contribute to the increase of mass in the animal body.
The chemical analysis of these three substances has led to the
interesting result that they contain the same organic elements, united
in the same proportion by weight; and--which is more remarkable--that
they are identical in composition with the chief constituents of
blood--animal fibrine and animal albumen. By identity, be it remarked,
is not here meant merely similarity, but that even in regard to the
presence and relative amounts of sulphur, phosphorus, and phosphate of
lime no difference can be observed.
How beautifully simple then, by the aid of these discoveries, appears
the process of nutrition in animals, the formation of their organs, in
which vitality chiefly resides. Those vegetable constituents which are
used by animals to form blood contain the essential ingredients of blood
ready formed. In point of fact, vegetables produce in their organism the
blood of all animals; for the carnivora, in consuming the blood and
flesh of the graminivora, consume, strictly speaking, the vegetable
principles which have served for the nourishment of the latter. In this
sense we may say the animal organism gives to blood only its form; and,
further, that it is incapable of forming blood out of other compounds
which do not contain the chief ingredients of that fluid.
Animal and vegetable life are, therefore, closely related, for the first
substance capable of affording nutriment to animals is the last product
of the creative energy of vegetables. The seemingly miraculous in the
nutritive power of vegetables disappears in a great degree, for the
production of the constituents of blood cannot appear more surprising
than the occurrence of the principal ingredient of butter in palm-oil
and of horse-fat and train-oil in certain of the oily seeds.
_IV.--Food the Fuel of Life_
We have still to account for the use in food of substances which are
destitute of nitrogen but are known to be necessary to animal life. Such
substances are starch, sugar, gum, and pectine. In all of these we find
a great excess of carbon, with oxygen and hydrogen in the same
proportion as water. They therefore add an excess of carbon to the
nitrogenised constituents of food, and they cannot possibly be employed
in the production of blood, because the nitrogenised compounds contained
in the food already contain exactly the amount of carbon which is
required for the production of fibrine and albumen. Now, it can be shown
that very little of the excess of this carbon is ever expelled in the
form either of solid or liquid compounds; it must be expelled,
therefore, in the gaseous state. In short, these compounds are solely
expended in the production of animal heat, being converted by the oxygen
of the air into carbonic acid and water. The food of carnivorous animals
does not contain non-nitrogenised matters, so that the carbon and
hydrogen necessary for the production of animal heat are furnished in
them from the waste of their tissues.
The transformed matters of the organs are obviously unfit for the
further nourishment of the body--that is, for the increase or
reproduction of the mass. They pass through the absorbent and lymphatic
vessels into the veins, and their accumulation in these would soon put a
stop to the nutritive process were it not that the blood has to pass
through a filtering apparatus, as it were, before reaching the heart.
The venous blood, before returning to the heart, is made to pass through
the liver and the kidneys, which separate from it all substances
incapable of contributing to nutrition. The new compounds containing the
nitrogen of the transformed organs, being utterly incapable of further
application in the system, are expelled from the body. Those which
contain the carbon of the transformed tissues are collected in the
gall-bladder as bile, a compound of soda which, being mixed with water,
passes through the duodenum and mixes with chyme. All the soda of the
bile, and ninety-nine-hundredths of the carbonaceous matter which it
contains, retain the capacity of re-absorption by the absorbents of the
small and large intestines--a capacity which has been proved by direct
experiment.
The globules of the blood, which in themselves can be shown to take no
share in the nutritive process, serve to transport the oxygen which they
give up in their passage through the capillary vessels. Here the current
of oxygen meets with the carbonaceous substances of the transformed
tissues, and converts their carbon into carbonic acid, their hydrogen
into water. Every portion of these substances which escapes this process
of oxidation is sent back into the circulation in the form of bile,
which by degrees completely disappears.
It is obvious that in the system of the graminivora, whose food contains
relatively so small a proportion of the constituents of blood, the
process of metamorphosis in existing tissues, and consequently their
restoration or reproduction, must go on far less rapidly than in the
carnivora. Otherwise, a vegetation a thousand times as luxuriant would
not suffice for their sustenance. Sugar, gum, and starch, which form so
large a proportion of their food, would then be no longer necessary to
support life in these animals, because in that case the products of
waste, or metamorphosis of organised tissues, would contain enough
carbon to support the respiratory process.
When exercise is denied to graminivorous and omnivorous animals this is
tantamount to a deficient supply of oxygen. The carbon of the food, not
meeting with a sufficient supply of oxygen to consume it, passes into
other compounds containing a large excess of carbon--or, in other words,
fat is produced. Fat is thus an abnormal production, resulting from a
disproportion of carbon in the food to that of the oxygen respired by
the lungs or absorbed by the skin. Wild animals in a state of nature do
not contain fat. The production of fat is always a consequence of a
deficient supply of oxygen, for oxygen is absolutely indispensable for
the dissipation of excess of carbon in the food.
_V.--Animal Life-Chemistry_
The substances of which the food of man is composed may be divided into
two classes--into nitrogenised and non-nitrogenised. The former are
capable of conversion into blood, the latter incapable of this
transformation. Out of those substances which are adapted to the
formation of blood are formed all the organised tissues. The other class
of substances in the normal state of health serve to support the process
of respiration. The former may be called the plastic elements of
nutrition; the latter, elements of respiration.
Among the former we may reckon--vegetable fibrine, vegetable albumen,
vegetable casein, animal flesh, animal blood.
Among the elements of respiration in our food are--fat, starch, gum,
cane sugar, grape-sugar, sugar of milk, pectine, bassorine, wine, beer,
spirits.
The nitrogenised constituents of vegetable food have a composition
identical with that of the constituents of the blood.
No nitrogenised compound the composition of which differs from that of
fibrine, albumen, and casein, is capable of supporting the vital process
in animals.
The animal organism undoubtedly possesses the power of forming from the
constituents of its blood the substance of its membranes and cellular
tissue, of the nerves and brain, of the organic part of cartilages and
bones. But the blood must be supplied to it ready in everything but its
form--that is, in its chemical composition. If this is not done, a
period is put to the formation of blood, and, consequently, to life.
The whole life of animals consists of a conflict between chemical forces
and the vital power. In the normal state of the body of an adult these
stand in equilibrium: that is, there is equilibrium between the
manifestations of the causes of waste and the causes of supply. Every
mechanical or chemical agency which disturbs the restoration of this
equilibrium is a cause of disease.
Death is that condition in which chemical or mechanical powers gain the
ascendancy, and all resistance on the part of the vital force ceases.
This resistance never entirely departs from living tissues during life.
Such deficiency in resistance is, in fact, a deficiency in resistance to
the action of the oxygen of the atmosphere.
Disease occurs when the sum of vital force, which tends to neutralise
all causes of disturbance, is weaker than the acting cause of
disturbance.
Should there be formed in the diseased parts, in consequence of the
change of matter, from the elements of the blood or of the tissue, new
products which the neighbouring parts cannot employ for their own vital
functions; should the surrounding parts, moreover, be unable to convey
these products to other parts where they may undergo transformation,
then these new products will suffer, at the place where they have been
formed, a process of decomposition analogous to putrefaction.
In certain cases, medicine removes these diseased conditions by exciting
in the vicinity of the diseased part, or in any convenient situation, an
artificial diseased state (as by blisters), thus diminishing by means of
artificial disturbance the resistance offered to the external causes of
change in these parts by the vital force. The physician succeeds in
putting an end to the original diseased condition when the disturbance
artificially excited (or the diminution of resistance in another part)
exceeds in amount the diseased state to be overcome.
The accelerated change of matter and the elevated temperature in the
diseased part show that the resistance offered by the vital force to the
action of oxygen is feebler than in the healthy state. But this
resistance only ceases entirely when death takes place. By the
artificial diminution of resistance in another part, the resistance in
the diseased organ is not, indeed, directly strengthened; but the
chemical action, the cause of the change of matter, is diminished in the
diseased part, being directed to another part, where the physician has
succeeded in producing a still more feeble resistance to the change of
matter, to the action of oxygen.
SIR CHARLES LYELL
The Principles of Geology
Sir Charles Lyell, the distinguished geologist, was born at
Kinnordy, Forfarshire, Scotland, Nov. 14, 1797. It was at Oxford
that his scientific interest was first aroused, and after taking an
M.A. degree in 1821 he continued his scientific studies, becoming
an active member of the Geological and Linnæan Societies of London.
In 1826 he was elected a fellow of the Royal Society, and two years
later went with Sir Roderick Murchison on a tour of Europe, and
gathered evidence for the theory of geological uniformity which he
afterwards promulgated. In 1830 he published his great work,
"Principles of Geology: Being an Attempt to Explain the Former
Changes of the Earth's Surface by References to Causes now in
Action," which converted almost the whole geological world to the
doctrine of uniformitarianism, and may be considered the foundation
of modern geology. Lyell died in London on February 22, 1875.
Besides his great work, he also published "The Elements of
Geology," "The Antiquity of Man," "Travels in North America," and
"The Student's Elements of Geology."
_I.--Uniformity in Geological Development_
According to the speculations of some writers, there have been in the
past history of the planet alternate periods of tranquillity and
convulsion, the former enduring for ages, and resembling the state of
things now experienced by man; the other brief, transient, and
paroxysmal, giving rise to new mountains, seas, and valleys,
annihilating one set of organic beings, and ushering in the creation of
another. These theories, however, are not borne out by a fair
interpretation of geological monuments; but, on the contrary, nature
indicates no such cataclysms, but rather progressive uniformity.
Igneous rocks have been supposed to afford evidence of ancient paroxysms
of nature, but we cannot consider igneous rocks proof of any
exceptional paroxysms. Rather, we find ourselves compelled to regard
igneous rocks as an aggregate effect of innumerable eruptions, of
various degrees of violence, at various times, and to consider mountain
chains as the accumulative results of these eruptions. The incumbent
crust of the earth is never allowed to attain that strength and
coherence which would be necessary in order to allow the volcanic force
to accumulate and form an explosive charge capable of producing a grand
paroxysmal eruption. The subterranean power, on the contrary, displays,
even in its most energetic efforts, an intermittent and mitigated
intensity. There are no proofs that the igneous rocks were produced more
abundantly at remote periods.
Nor can we find proof of catastrophic discontinuity when we examine
fossil plants and fossil animals. On the contrary, we find a progressive
development of organic life at successive geological periods.
In Palæozoic strata the entire want of plants of the most complex
organisation is very striking, for not a single dicotyledonous
angiosperm has yet been found, and only one undoubted monocotyledon. In
Secondary, or Mesozoic, times, palms and some other monocotyledons
appeared; but not till the Upper Cretaceous era do we meet with the
principal classes and orders of the vegetable kingdom as now known.
Through the Tertiary ages the forms were perpetually changing, but
always becoming more and more like, generically and specifically, to
those now in being. On the whole, therefore, we find progressive
development of plant life in the course of the ages.
In the case of animal life, progression is equally evident.
Palæontological research leads to the conclusion that the invertebrate
animals flourished before the vertebrate, and that in the latter class
fish, reptiles, birds, and mammalia made their appearance in a
chronological order analogous to that in which they would be arranged
zoologically according to an advancing scale of perfection in their
organisation. In regard to the mammalia themselves, they have been
divided by Professor Owen into four sub-classes by reference to
modifications of their brain. The two lowest are met with in the
Secondary strata. The next in grade is found in Tertiary strata. And the
highest of all, of which man is the sole representative, has not yet
been detected in deposits older than the Post-Tertiary.
It is true that in passing from the older to the newer members of the
Tertiary system we meet with many chasms, but none which separate
entirely, by a broad line of demarcation, one state of the organic world
from another. There are no signs of an abrupt termination of one fauna
and flora, and the starting into life of new and wholly distinct forms.
Although we are far from being able to demonstrate geologically an
insensible transition from the Eocene to the Miocene, or even from the
latter to the recent fauna, yet the more we enlarge and perfect our
general survey the more nearly do we approximate to such a continuous
series, and the more gradually are we conducted from times when many of
the genera and nearly all the species were extinct to those in which
scarcely a single species flourished which we do not know to exist at
present. We must remember, too, that many gaps in animal and floral life
were due to ordinary climatic and geological factors. We could, under no
circumstances, expect to meet with a complete ascending series.
The great vicissitudes in climate which the earth undoubtedly
experienced, as shown by geological records, have been held to be
themselves proof of sudden violent revolutions in the life-history of
the world. But all the great climatic vicissitudes can be accounted for
by the action of factors still, in operation--subsidences and elevations
of land, alterations in the relative proportions and position of land
and water, variations in the relative position of our planet to the sun
and other heavenly bodies.
Altogether, the conclusion is inevitable that from the remotest period
there has been one uniform and continuous system of change in the
animate and inanimate world, and accordingly every fact collected
respecting the factors at present at work in forming and changing the
world, affords a key to the interpretation of its part. And thus,
although we are mere sojourners on the surface of the planet, chained to
a mere point in space, enduring but for a moment of time, the human mind
is enabled not only to number worlds beyond the unassisted ken of mortal
eye, but to trace the events of indefinite ages before the creation of
our race, and to penetrate into the dark secrets of the ocean and the
heart of the solid globe.
_II.--Changes in the Inorganic World now in Progress_
The great agents of change in the inorganic world may be divided into
two principal classes--the aqueous and the igneous. To the aqueous
belong rain, rivers, springs, currents, and tides, and the action of
frost and snow; to the igneous, volcanoes and earthquakes. Both these
classes are instruments of degradation as well as of reproduction. But
they may also be regarded as antagonist forces, since the aqueous agents
are incessantly labouring to reduce the inequalities of the earth's
surface to a level; while the igneous are equally active in restoring
the unevenness of the external crust, partly by heaping up new matter in
certain localities, and partly by depressing one portion of the earth's
envelope and forcing out another.
We will treat in the first place of the aqueous agents.
RAIN AND RIVERS. When one considers that in some parts of the world as
much as 500 or 600 inches of rain may fall annually, it is easy to
believe that rain _qua_ rain may be a denuding and plastic agent, and in
some parts of the world we find evidence of its action in earth pillars
or pyramids. The best example of earth pillars is seen near Botzen, in
the Tyrol, where there are hundreds of columns of indurated mud, varying
in height from 20 feet to 100 feet. These columns are usually capped by
a single stone, and have been separated by rain from the terrace of
which they once formed a part.
As a rule, however, rain acts through rivers. The power of rivers to
denude and transport is exemplified daily. Even a comparatively small
stream when swollen by rain may move rocks tons in weight, and may
transport thousands of tons of gravel. The greatest damage is done when
rivers are dammed by landslips or by ice. In 1818 the River Dranse was
blocked by ice, and its upper part became a lake. In the hot season the
barrier of ice gave way, and the torrent swept before it rocks, forests,
houses, bridges, and cultivated land. For the greater part of its course
the flood resembled a moving mass of rock and mud rather than of water.
Some fragments of granite rock of enormous size, which might be compared
to houses, were torn out and borne down for a quarter of a mile.
The rivers of unmelted ice called the glaciers act more slowly, but they
also have the power of transporting gravel, sand, and boulders to great
distances, and of polishing and scoring their rocky channels. Icebergs,
too, are potent geological agents. Many of them are loaded with 50,000
to 100,000 tons of rock and earth, which they may carry great distances.
Also in their course they must break, and polish, and scratch the peaks
and points of submarine mountains.
Coast ice, likewise, may transport rocks and earth. Springs also must be
considered as geological agents affecting the face of the globe.
But running water not only denudes it, but also creates land, for
lakes, seas, rivers are seen to form deltas. That Egypt was the gift of
the Nile was the opinion of the Egyptian priests, and there can be no
doubt that the fertility of the alluvial plain above Cairo, and the very
existence of the delta below that city, are due to the action of that
great river, and to its power of transporting mud from the interior of
Africa and depositing it on its inundated plains as well as on that
space which has been reclaimed from the Mediterranean and converted into
land. The delta of the Ganges and Brahmapootra is more than double that
of the Nile. Even larger is the delta of the Mississippi, which has been
calculated to be 12,300 square miles in area.
TIDES AND CURRENTS. The transporting and destroying and constructive
power of tides and currents is, in many respects, analogous to that of
rivers, but extends to wider areas, and is, therefore, of more
geological importance. The chief influence of the ocean is exerted at
moderate depths below the surface on all areas which are slowly rising,
or attempting, as it were, to rise above the sea; but its influence is
also seen round the coast of every continent and island.
* * * * *
We shall now consider the igneous agents that act on the earth's
surface. These agents are chiefly volcanoes and earthquakes, and we find
that both usually occur in particular parts of the world. At various
times and at various places within historical times volcanic eruptions
and earthquakes have both proved their potency to alter the face of the
earth.
The principal geological facts and theories with regard to volcanoes and
earthquakes are as follows.
The primary causes of the volcano and the earthquake are to a great
extent the same, and connected with the development of heat and chemical
action at various depths in the interior of the globe.
Volcanic heat has been supposed to be the result of the original high
temperature of the molten planet, and the planet has been supposed to
lose heat by radiation. Recent inquiries, however, suggest that the
apparent loss of heat may arise from the excessive local development of
volcanic action.
Whatever the original shape of our planet, it must in time have become
spheroidal by the gradual operation of centrifugal force acting on
yielding materials brought successively within its action by aqueous and
igneous causes.
The heat in mines and artesian wells increases as we descend, but not in
uniform ratio in different regions. Increase at a uniform ratio would
imply such heat in the central nucleus as must instantly fuse the crust.
Assuming that there are good astronomical grounds for inferring the
original fluidity of the planet, yet such pristine fluidity need not
affect the question of volcanic heat, for the volcanic action of
successive periods belongs to a much more modern state of the globe, and
implies the melting of different parts of the solid crust one after the
other.
The supposed great energy of the volcanic forces in the remoter periods
is by no means borne out by geological observations on the quantity of
lava produced by single eruptions in those several periods.
The old notion that the crystalline rocks, whether stratified or
unstratified, such as granite and gneiss, were produced in the lower
parts of the earth's crust at the expense of a central nucleus slowly
cooling from a state of fusion by heat has now had to be given up, now
that granite is found to be of all ages, and now that we know the
metamorphic rocks to be altered sedimentary strata, implying the
denudation of a previously solidified crust.
The powerful agency of steam or aqueous vapour in volcanic eruptions
leads us to compare its power of propelling lava to the surface with
that which it exerts in driving water up the pipe of an Icelandic
geyser. Various gases also, rendered liquid by pressure at great depths,
may aid in causing volcanic outbursts, and in fissuring and convulsing
the rocks during earthquakes.
The chemical character of the products of recent eruptions suggests that
large bodies of salt water gain access to the volcanic foci. Although
this may not be the primary cause of volcanic eruptions, which are
probably due to the aqueous vapour intimately mixed with molten rock,
yet once the crust is shattered through, the force and frequency of
eruptions may depend in some measure on the proximity of large bodies of
water.
The permanent elevation and subsidence of land now observed, and which
may have been going on through past ages, may be connected with the
expansion and contraction of parts of the solid crust, some of which
have been cooling from time to time, while others have been gaining
heat.
In the preservation of the average proportion of land and sea, the
igneous agents exert a conservative power, restoring the unevenness of
the surface which the levelling power of water in motion would tend to
destroy. If the diameter of the planet remains always the same, the
downward movements of the crust must be somewhat in excess, to
counterbalance the effects of volcanoes and mineral springs, which are
always ejecting material so as to raise the level of the surface of the
earth. Subterranean movements, therefore, however destructive they may
be during great earthquakes, are essential to the well-being of the
habitable surface, and even to the very existence of terrestrial and
aquatic species.
_III.--Changes of the Organic World now in Progress_
In 1809 Lamarck introduced the idea of transmutation of species,
suggesting that by changes in habitat, climate, and manner of living one
species may, in the course of generations, be transformed into a new
and distinct species.
In England, however, the idea remained dormant till in 1844 a work
entitled the "Vestiges of Creation" reinforced it with many new facts.
In this work the unity of plan exhibited by the whole organic creation,
fossil and recent, and the mutual affinities of all the different
classes of the animal and vegetable kingdoms, were declared to be in
harmony with the idea of new forms having proceeded from older ones by
the gradually modifying influence of environment. In 1858 the theory was
put on a new and sound basis by Wallace and Darwin, who added the
conception of natural selection, suggesting that variations in species
are naturally produced, and that the variety fittest to survive in the
severe struggle for existence must survive, and transmit the
advantageous variation, implying the gradual evolution of new species.
Further, Darwin showed that other varieties may be perpetuated by sexual
selection.
On investigating the geographical distribution of animals and plants we
find that the extent to which the species of mammalia, birds, insects,
landshells, and plants (whether flowering or cryptogamous) agree with
continental species; or the degree in which those of different islands
of the same group agree with each other has an unmistakable relation to
the known facilities enjoyed by each class of crossing the ocean. Such a
relationship accords well with the theory of variation and natural
selection, but with no other hypothesis yet suggested for explaining the
origin of species.
From what has been said of the changes which are always going on in the
habitable surface of the world, and the manner in which some species are
constantly extending their range at the expense of others, it is evident
that the species existing at any particular period may, in the course of
ages, become extinct one after the other.
If such, then, be the law of the organic world, if every species is
continually losing some of its varieties, and every genus some of its
species, it follows that the transitional links which once, according to
the doctrine of transmutation, must have existed, will, in the great
majority of cases, be missing. We learn from geological investigations
that throughout an indefinite lapse of ages the whole animate creation
has been decimated again and again. Sometimes a single representative
alone remains of a type once dominant, or of which the fossil species
may be reckoned by hundreds. We rarely find that whole orders have
disappeared, yet this is notably the case in the class of reptiles,
which has lost some orders characterised by a higher organisation than
any now surviving in that class. Certain genera of plants and animals
which seem to have been wholly wanting, and others which were feebly
represented in the Tertiary period, are now rich in species, and appear
to be in such perfect harmony with the present conditions of existence
that they present us with countless varieties, confounding the zoologist
or botanist who undertakes to describe or classify them.
We have only to reflect on the causes of extinction, and we at once
foresee the time when even in these genera so many gaps will occur, so
many transitional forms will be lost, that there will no longer be any
difficulty in assigning definite limits to each surviving species. The
blending, therefore, of one generic or specific form into another must
be an exception to the general rule, whether in our own time or in any
period of the past, because the forms surviving at any given moment will
have been exposed for a long succession of antecedent periods to those
powerful causes of extinction which are slowly but incessantly at work
in the organic and inorganic worlds.
They who imagine that, if the theory of transmutation be true, we ought
to discover in a fossil state all the intermediate links by which the
most dissimilar types have been formerly connected together, expect a
permanence and completeness of records such as is never found. We do not
find even that all recently extinct plants have left memorials of their
existence in the crust of the earth; and ancient archives are certainly
extremely defective. To one who is aware of the extreme imperfection of
the geological record, the discovery of one or two missing links is a
fact of small significance; but each new form rescued from oblivion is
an earnest of the former existence of hundreds of species, the greater
part of which are irrevocably lost.
A somewhat serious cause of disquiet and alarm arises out of the
supposed bearing of this doctrine of the origin of species by
transmutation on the origin of man, and his place in nature. It is
clearly seen that there is such a close affinity, such an identity in
all essential points, in our corporeal structure, and in many of our
instincts and passions with those of the lower animals--that man is so
completely subjected to the same general laws of reproduction, increase,
growth, disease, and death--that if progressive development, spontaneous
variation, and natural selection have for millions of years directed the
changes of the rest of the organic world, we cannot expect to find that
the human race has been exempted from the same continuous process of
evolution.
Such a near bond of connection between man and the rest of the animate
creation is regarded by many as derogatory to our dignity. But we have
already had to exchange the pleasing conceptions indulged in by poets
and theologians as to the high position in the scale of being held by
our early progenitors for humble and more lowly beginnings, the joint
labours of the geologist and archæologist having left us in no doubt of
the ignorance and barbarism of Palæolithic man.
It is well, too, to remember that the high place we have reached in the
scale of being has been gained step by step, by a conscientious study
of natural phenomena, and by fearlessly teaching the doctrines to which
they point. It is by faithfully weighing evidence without regard to
preconceived notions, by earnestly and patiently searching for what is
true, not what we wish to be true, that we have attained to that
dignity, which we may in vain hope to claim through the rank of an ideal
parentage.
JAMES CLERK MAXWELL
A Treatise on Electricity and Magnetism
James Clerk Maxwell, the first professor of experimental physics at
Cambridge, was born at Edinburgh on November 13, 1831, and before
he was fifteen was already famous as a writer of scientific papers.
In 1854 he graduated at Cambridge as second wrangler. Two years
later he became professor of natural philosophy at Marischal
College, Aberdeen. Vacating his chair in 1860 for one at King's
College, London, Maxwell contributed largely to scientific
literature. His great lifework, however, is his famous "Treatise on
Electricity and Magnetism," which was published in 1873, and is, in
the words of a critic, "one of the most splendid monuments ever
raised by the genius of a single individual." It was in this work
that he constructed his famous theory if electricity in which
"action at a distance" should be replaced by "action through a
medium," and first enunciated the principles of an electro-magnetic
theory of light which has formed the basis of nearly all modern
physical science. He died on November 5, 1879.
_I.--The Nature of Electricity_
Let a piece of glass and a piece of resin be rubbed together. They will
be found to attract each other. If a second piece of glass be rubbed
with a second piece of resin, it will be found that the two pieces of
glass repel each other and that the two pieces of resin are also
repelled from one another, while each piece of glass attracts each piece
of resin. These phenomena of attraction and repulsion are called
electrical phenomena, and the bodies which exhibit them are said to be
"electrified," or to be "charged with electricity."
Bodies may be electrified in many other ways, as well as by friction.
When bodies not previously electrified are observed to be acted on by an
electrified body, it is because they have become "electrified by
induction." If a metal vessel be electrified by induction, and a second
metallic body be suspended by silk threads near it, and a metal wire be
brought to touch simultaneously the electrified body and the second
body, this latter body will be found to be electrified. Electricity has
been transferred from one body to the other by means of the wire.
There are many other manifestations of electricity, all of which have
been more or less studied, and they lead to the formation of theories of
its nature, theories which fit in, to a greater or less extent, with the
observed facts. The electrification of a body is a physical quantity
capable of measurement, and two or more electrifications can be combined
experimentally with a result of the same kind as when two quantities are
added algebraically. We, therefore, are entitled to use language fitted
to deal with electrification as a quantity as well as a quality, and to
speak of any electrified body as "charged with a certain quantity of
positive or negative electricity."
While admitting electricity to the rank of a physical quantity, we must
not too hastily assume that it is, or is not, a substance, or that it
is, or is not, a form of energy, or that it belongs to any known
category of physical quantities. All that we have proved is that it
cannot be created or annihilated, so that if the total quantity of
electricity within a closed surface is increased or diminished, the
increase or diminution must have passed in or out through the closed
surface.
This is true of matter, but it is not true of heat, for heat may be
increased or diminished within a closed surface, without passing in or
out through the surface, by the transformation of some form of energy
into heat, or of heat into some other form of energy. It is not true
even of energy in general if we admit the immediate action of bodies at
a distance.
There is, however, another reason which warrants us in asserting that
electricity, as a physical quantity, synonymous with the total
electrification of a body, is not, like heat, a form of energy. An
electrified system has a certain amount of energy, and this energy can
be calculated. The physical qualities, "electricity" and "potential,"
when multiplied together, produce the quantity, "energy." It is
impossible, therefore, that electricity and energy should be quantities
of the same category, for electricity is only one of the factors of
energy, the other factor being "potential."
Electricity is treated as a substance in most theories of the subject,
but as there are two kinds of electrification, which, being combined,
annul each other, a distinction has to be drawn between free electricity
and combined electricity, for we cannot conceive of two substances
annulling each other. In the two-fluid theory, all bodies, in their
unelectrified state, are supposed to be charged with equal quantities of
positive and negative electricity. These quantities are supposed to be
so great than no process of electrification has ever yet deprived a body
of all the electricity of either kind. The two electricities are called
"fluids" because they are capable of being transferred from one body to
another, and are, within conducting bodies, extremely mobile.
In the one-fluid theory everything is the same as in the theory of two
fluids, except that, instead of supposing the two substances equal and
opposite in all respects, one of them, generally the negative one, has
been endowed with the properties and name of ordinary matter, while the
other retains the name of the electric fluid. The particles of the fluid
are supposed to repel each other according to the law of the inverse
square of the distance, and to attract those of matter according to the
same law. Those of matter are supposed to repel each other and attract
those of electricity. This theory requires us, however, to suppose the
mass of the electric fluid so small that no attainable positive or
negative electrification has yet perceptibly increased or diminished the
mass or the weight of a body, and it has not yet been able to assign
sufficient reasons why the positive rather than the negative
electrification should be supposed due to an _excess_ quantity of
electricity.
For my own part, I look for additional light on the nature of
electricity from a study of what takes place in the space intervening
between the electrified bodies. Some of the phenomena are explained
equally by all the theories, while others merely indicate the peculiar
difficulties of each theory. We may conceive the relation into which the
electrified bodies are thrown, either as the result of the state of the
intervening medium, or as the result of a direct action between the
electrified bodies at a distance. If we adopt the latter conception, we
may determine the law of the action, but we can go no further in
speculating on its cause.
If, on the other hand, we adopt the conception of action through a
medium, we are led to inquire into the nature of that action in each
part of the medium. If we calculate on this hypothesis the total energy
residing in the medium, we shall find it equal to the energy due to the
electrification of the conductors on the hypothesis of direct action at
a distance. Hence, the two hypotheses are mathematically equivalent.
On the hypothesis that the mechanical action observed between
electrified bodies is exerted through and by means of the medium, as the
action of one body on another by means of the tension of a rope or the
pressure of a rod, we find that the medium must be in a state of
mechanical stress. The nature of the stress is, as Faraday pointed out,
a tension along the lines of force combined with an equal pressure in
all directions at right angles to these lines. This distribution of
stress is the only one consistent with the observed mechanical action on
the electrified bodies, and also with the observed equilibrium of the
fluid dielectric which surrounds them. I have, therefore, assumed the
actual existence of this state of stress.
Every case of electrification or discharge may be considered as a
motion in a closed circuit, such that at every section of the circuit
the same quantity of electricity crosses in the same time; and this is
the case, not only in the voltaic current, where it has always been
recognised, but in those cases in which electricity has been generally
supposed to be accumulated in certain places. We are thus led to a very
remarkable consequence of the theory which we are examining, namely,
that the motions of electricity are like those of an _incompressible_
fluid, so that the total quantity within an imaginary fixed closed
surface remains always the same.
The peculiar features of the theory as developed in this book are as
follows.
That the energy of electrification resides in the dielectric medium,
whether that medium be solid or gaseous, dense or rare, or even deprived
of ordinary gross matter, provided that it be still capable of
transmitting electrical action.
That the energy in any part of the medium is stored up in the form of a
constraint called polarisation, dependent on the resultant electromotive
force (the difference of potentials between two conductors) at the
place.
That electromotive force acting on a dielectric produces what we call
electric displacement.
That in fluid dielectrics the electric polarisation is accompanied by a
tension in the direction of the lines of force combined with an equal
pressure in all directions at right angles to the lines of force.
That the surfaces of any elementary portion into which we may conceive
the volume of the dielectric divided must be conceived to be
electrified, so that the surface density at any point of the surface is
equal in magnitude to the displacement through that point of the surface
_reckoned inwards_.
That, whatever electricity may be, the phenomena which we have called
electric displacement is a movement of electricity in the same sense as
the transference of a definite quantity of electricity through a wire.
_II.--Theories of Magnetism_
Certain bodies--as, for instance, the iron ore called loadstone, the
earth itself, and pieces of steel which have been subjected to certain
treatment--are found to possess the following properties, and are called
magnets.
If a magnet be suspended so as to turn freely about a vertical axis, it
will in general tend to set itself in a certain azimuth, and, if
disturbed from this position, it will oscillate about it.
It is found that the force which acts on the body tends to cause a
certain line in the body--called the axis of the magnet--to become
parallel to a certain line in space, called the "direction of the
magnetic force."
The ends of a long thin magnet are commonly called its poles, and like
poles repel each other; while unlike poles attract each other. The
repulsion between the two magnetic poles is in the straight line joining
them, and is numerically equal to the products of the strength of the
poles divided by the square of the distance between them; that is, it
varies as the inverse square of the distance. Since the form of the law
of magnetic action is identical with that of electric action, the same
reasons which can be given for attributing electric phenomena to the
action of one "fluid," or two "fluids" can also be used in favour of the
existence of a magnetic matter, fluid or otherwise, provided new laws
are introduced to account for the actual facts.
At all parts of the earth's surface, except some parts of the polar
regions, one end of a magnet points in a northerly direction and the
other in a southerly one. Now a bar of iron held parallel to the
direction of the earth's magnetic force is found to become magnetic. Any
piece of soft iron placed in a magnetic field is found to exhibit
magnetic properties. These are phenomena of _induced_ magnetism. Poisson
supposes the magnetism of iron to consist in a separation of the
magnetic fluids within each magnetic molecule. Weber's theory differs
from this in assuming that the molecules of the iron are always magnets,
even before the application of the magnetising force, but that in
ordinary iron the magnetic axes of the molecules are turned
indifferently in every direction, so that the iron as a whole exhibits
no magnetic properties; and this theory agrees very well with what is
observed.
The theories establish the fact that magnetisation is a phenomenon, not
of large masses of iron, but of molecules; that is to say, of portions
of the substance so small that we cannot by any mechanical method cut
them in two, so as to obtain a north pole separate from the south pole.
We have arrived at no explanation, however, of the nature of a magnetic
molecule, and we have therefore to consider the hypothesis of
Ampère--that the magnetism of the molecule is due to an electric current
constantly circulating in some closed path within it.
Ampère concluded that if magnetism is to be explained by means of
electric currents, these currents must circulate within the molecules of
the magnet, and cannot flow from one molecule to another. As we cannot
experimentally measure the magnetic action at a point within the
molecule, this hypothesis cannot be disproved in the same way that we
can disprove the hypothesis of sensible currents within the magnet. In
spite of its apparent complexity, Ampère's theory greatly extends our
mathematical vision into the interior of the molecules.
_III.--The Electro-Magnetic Theory of Light_
We explain electro-magnetic phenomena by means of mechanical action
transmitted from one body to another by means of a medium occupying the
space between them. The undulatory theory of light also assumes the
existence of a medium. We have to show that the properties of the
electro-magnetic medium are identical with those of the luminiferous
medium.
To fill all space with a new medium whenever any new phenomena are to be
explained is by no means philosophical, but if the study of two
different branches of science has independently suggested the idea of a
medium; and if the properties which must be attributed to the medium in
order to account for electro-magnetic phenomena are of the same kind as
those which we attribute to the luminiferous medium in order to account
for the phenomena of light, the evidence for the physical existence of
the medium is considerably strengthened.
According to the theory of emission, the transmission of light energy is
effected by the actual transference of light-corpuscles from the
luminous to the illuminated body. According to the theory of undulation
there is a material medium which fills the space between the two bodies,
and it is by the action of contiguous parts of this medium that the
energy is passed on, from one portion to the next, till it reaches the
illuminated body. The luminiferous medium is therefore, during the
passage of light through it, a receptacle of energy. This energy is
supposed to be partly potential and partly kinetic, and our theory
agrees with the undulatory theory in assuming the existence of a medium
capable of becoming a receptacle for two forms of energy.
Now, the properties of bodies are capable of quantitative measurement.
We therefore obtain the numerical value of some property of the
medium--such as the velocity with which a disturbance is propagated in
it, which can be calculated from experiments, and also observed directly
in the case of light. If it be found that the velocity of propagation of
electro-magnetic disturbance is the same as the velocity of light, we
have strong reasons for believing that light is an electro-magnetic
phenomenon.
It is, in fact, found that the velocity of light and the velocity of
propagation of electro-magnetic disturbance are quantities of the same
order of magnitude. Neither of them can be said to have been determined
accurately enough to say that one is greater than the other. In the
meantime, our theory asserts that the quantities are equal, and assigns
a physical reason for this equality, and it is not contradicted by the
comparison of the results, such as they are.
Lorenz has deduced from Kirchoff's equations of electric currents a new
set of equations, indicating that the distribution of force in the
electro-magnetic field may be considered as arising from the mutual
action of contiguous elements, and that waves, consisting of transverse
electric currents, may be propagated, with a velocity comparable with
that of light, in non-conducting media. These conclusions are similar to
my own, though obtained by an entirely different method.
The most important step in establishing a relation between electric and
magnetic phenomena and those of light must be the discovery of some
instance in which one set of phenomena is affected by the other. Faraday
succeeded in establishing such a relation, and the experiments by which
he did so are described in the nineteen series of his "Experimental
Researches." Suffice it to state here that he showed that in the case of
aray of plane-polarised light the effect of the magnetic force is to
turn the plane of polarisation round the direction of the ray as an
axis, through a certain angle.
The action of magnetism on polarised light leads to the conclusion that
in a medium under the action of a magnetic force, something belonging to
the same mathematical class as an angular velocity, whose axis is in the
direction of the magnetic force, forms part of the phenomenon. This
angular velocity cannot be any portion of the medium of sensible
dimensions rotating as a whole. We must, therefore, conceive the
rotation to be that of very small portions of the medium, each rotating
on its own axis.
This is the hypothesis of molecular vortices. The displacements of the
medium during the propagation of light will produce a disturbance of the
vortices, and the vortices, when so disturbed, may react on the medium
so as to affect the propagation of the ray. The theory proposed is of a
provisional kind, resting as it does on unproved hypotheses relating to
the nature of molecular vortices, and the mode in which they are
affected by the displacement of the medium.
_IV.--Action at a Distance_
There appears to be some prejudice, or _a priori_ objection, against the
hypothesis of a medium in which the phenomena of radiation of light and
heat, and the electric actions at a distance, take place. It is true
that at one time those who speculated as to the cause of physical
phenomena were in the habit of accounting for each kind of action at a
distance by means of a special æthereal fluid, whose function and
property it was to produce these actions. They filled all space three
and four times over with æthers of different kinds, the properties of
which consisted merely to "save appearances," so that more rational
inquirers were willing to accept not only Newton's definite law of
attraction at a distance, but even the dogma of Cotes that action at a
distance is one of the primary properties of matter, and that no
explanation can be more intelligible than this fact. Hence the
undulatory theory of light has met with much opposition, directed not
against its failure to explain the phenomena, but against its assumption
of the existence of a medium in which light is propagated.
The mathematical expression for electro-dynamic action led, in the mind
of Gauss, to the conviction that a theory of the propagation of electric
action would in time be found to be the very keystone of
electro-dynamics. Now, we are unable to conceive of propagation in time,
except either as the flight of a material substance through space or as
the propagation of a condition of motion or stress in a medium already
existing in space.
In the theory of Neumann, the mathematical conception called potential,
which we are unable to conceive as a material substance, is supposed to
be projected from one particle to another, in a manner which is quite
independent of a medium, and which, as Neumann has himself pointed out,
is extremely different from that of the propagation of light. In other
theories it would appear that the action is supposed to be propagated in
a manner somewhat more similar to that of light.
But in all these theories the question naturally occurs: "If something
is transmitted from one particle to another at a distance, what is its
condition after it had left the one particle, and before it reached the
other?" If this something is the potential energy of the two particles,
as in Neumann's theory, how are we to conceive this energy as existing
in a point of space coinciding neither with the one particle nor with
the other? In fact, whenever energy is transmitted from one body to
another in time, there must be a medium or substance in which the energy
exists after it leaves one body, and before it reaches the other, for
energy, as Torricelli remarked, "is a quintessence of so subtile a
nature that it cannot be contained in any vessel except the inmost
substance of material things."
Hence all these theories lead to the conception of a medium in which the
propagation takes place, and if we admit this medium as an hypothesis, I
think we ought to endeavour to construct a mental representation of all
the details of its action, and this has been my constant aim in this
treatise.
ELIE METCHNIKOFF
The Nature of Man
Elie Metchnikoff, Sub-Director of the Pasteur Institute in Paris,
was born May 15, 1845, in the province of Kharkov, Russia, and has
worked at the Pasteur Institute since 1888. The greater part of
Metchnikoff's work is concerned with the most intimate processes of
the body, and notably the means by which it defends itself from the
living agents of disease. He is, indeed, the author of a standard
treatise entitled "Immunity in Infective Diseases." His early work
in zoology led him to study the water-flea, and thence to discover
that the white cells of the human blood oppose, consume, and
destroy invading microbes. Latterly, Metchnikoff has devoted
himself in some measure to more general and especially
philosophical studies, the outcome of which is best represented by
the notable volume on "The Nature of Man," which was published at
Paris in 1903.
_I.--Disharmonies in Nature_
Notwithstanding the real advance made by science, it cannot be disputed
that a general uneasiness disturbs the whole world to-day, and the
frequency of suicide is increased greatly among civilised peoples. Yet
if science turns to study human nature, there may be grounds for hope.
The Greeks held human nature and the human body in high esteem, and
among the Romans such a philosopher as Seneca said, "Take nature as your
guide, for so reason bids you and advises you; to live happily is to
live naturally." In our own day Herbert Spencer has expressed again the
Greek ideal, seeking the foundation of morality in human nature itself.
But it has often been taught that human nature is composed of two
hostile elements, a body and a soul. The soul alone was to be honoured,
while the body was regarded as the vile source of evils. This doctrine
has had many disastrous consequences, and it is not surprising that in
consequence of it celibacy should have been regarded as the ideal state.
Art fell from the Greek ideal until the Renaissance, with its return to
that ideal, brought new vigour. When the ancient spirit was born again
its influence reached science and even religion, and the Reformation was
a defence of human nature. The Lutheran doctrines resumed the principle
of a "development as complete as possible of all the natural powers" of
man, and compulsory celibacy was abolished.
The historical diversity of opinion regarding human nature is what has
led me to the attempt to give an exposition of human nature in its
strength and in its weakness. But, before dealing with the man himself,
we must survey the lower forms of life.
The facts of the organised world, before the appearnace of man, teach us
that though we find change and development, development does not always
take a progressive march. We are bound to believe, for instance, that
the latest products of evolution are not human beings, but certain
parasites which live only upon, or in, the human body. The law in nature
is not of constant progress, but of constant tendency towards
adaptation. Exquisite adaptations, or harmonies, in nature are
constantly met with in the world of living beings. But, on the other
hand, any close investigation of organisation and life reveals that
beside many most perfect harmonies, there are facts which prove the
existence of incomplete harmony, or even absolute disharmony.
Rudimentary and useless organs are widely distributed. Many insects are
exquisitely adapted for sucking the nectar of flowers; many others would
wish to do the same, but their want of adaptation baffles them.
It is plain that an instinct, or any other form of disharmony, leading
to destruction, cannot increase or even endure very long. The perversion
of the maternal instinct, tending to abandonment of the young, is
destructive to the stock. In consequence, individuals affected by it do
not have the opportunity of transmitting the perversion. If all rabbits,
or a majority of them, left their young to die through neglect, it is
evident that the species would soon die out. On the contrary, mothers
guided by their instinct to nourish and foster their offspring will
produce a vigorous generation capable of transmitting the healthy
maternal instinct so essential for the preservation of the species. For
such a reason harmonious characters are more abundant in nature than
injurious peculiarities. The latter, because they are injurious to the
individual and to the species, cannot perpetuate themselves
indefinitely.
In this way there comes about a constant selection of characters. The
useful qualities are handed down and preserved, while noxious characters
perish and so disappear. Although disharmonies tend to the destruction
of a species, they may themselves disappear without having destroyed the
race in which they occur.
This continuous process of natural selection, which offers so good an
explanation of the transmutation and origin of species by means of
preservation of useful and destruction of harmful characters, was
discovered by Darwin and Wallace, and was established by the splendid
researches of the former of these.
Long before the appearance of man on the face of the earth, there were
some happy beings well adapted to their environment, and some unhappy
creatures that followed disharmonious instincts so as to imperil or to
destroy their lives. Were such creatures capable of reflection and
communication, plainly the fortunate among them, such as orchids and
certain wasps, would be on the side of the optimists; they would declare
this the best of all possible worlds, and insist that to secure
happiness it is necessary only to follow natural instincts. On the other
hand, the disharmonious creatures, those ill adapted to the conditions
of life, would be pessimistic philosophers. Consider the case of the
ladybird, driven by hunger and with a preference for honey, which
searches for it on flowers and meets only with failure, or of insects
driven by their instincts into the flames, only to lose their wings and
their lives; such creatures, plainly, would express as their idea of the
world that it was fashioned abominably, and that existence was a
mistake.
_II.--Disharmonies in Man_
As for man, the creature most interesting to us, in what category does
he fall? Is he a being whose nature is in harmony with the conditions in
which he has to live, or is he out of harmony with his environment? A
critical examination is needed to answer these questions, and to such an
examination the pages to follow are devoted.
Science has proved that man is closely akin to the higher monkeys or
anthropoid apes--a fact which we must reckon with if we are to
understand human nature. The details of anatomy which show the kinship
between man and the apes are numerous and astonishing. All the facts
brought to light during the last forty years have supported this truth,
and no single fact has been brought against it. Quite lately it has been
shown that there are remarkable characters in the blood, such that,
though by certain tests the fluid part of human blood can be readily
distinguished from that of any other creature, the anthropoid apes, and
they alone, furnish an exception to this rule. There is thus verily a
close blood-relationship between the human species and the anthropoid
apes.
But how man arose we do not know. It is probable that he owes his origin
to a mutation--a sudden change comparable with that which De Vries
observed in the case of the evening primrose. The new creature possessed
a brain of abnormal size placed in a spacious cranium which allowed a
rapid development of intellectual faculties. This peculiarity would be
transmitted to the descendants, and as it was a very considerable
advantage in the struggle for existence, the new race would hold its
own, propagate, and prevail.
Although he is a recent arrival on the earth, man has already made great
progress, as compared with his ancestors the anthropoid apes, and we
learn the same if we compare the higher and lower races of mankind. Yet
there remain many disharmonies in the organisation of man, as, for
instance, in his digestive system. A simple instance of this kind is
furnished by the wisdom teeth. The complete absence of all four wisdom
teeth has no influence on mastication, and their presence is very
frequently the source of illness and danger. In man they are indeed
rudimentary organs, providing another proof of our simian origin. The
vermiform appendix, so frequently the cause of illness and death, is
another rudimentary organ in the human body, together with the part of
the digestive canal to which it is attached. The organ is a very old
part of the constitution of mammals, and it is because it has been
preserved long after its function has disappeared that we find it
occurring in the body of man.
I believe that not only the appendix, but a very large part of the
alimentary canal is superfluous, and worse than superfluous. It is, of
course, of great importance to the horse, the rabbit, and some other
mammals that live exclusively on grain and herbage. The latter part of
the alimentary canal, however, must be regarded as one of the organs
possessed by man and yet harmful to his health and life. It is the cause
of a series of misfortunes. The human stomach also is of little value,
and can easily be dispensed with, as surgery has proved. It is because
we inherit our alimentary canal from creatures of different dietetic
habits that it is impossible for us to take our nutriment in the most
perfect form. If we were only to eat substances that could be almost
completely absorbed, serious complications would be produced. A
satisfactory system of diet has to make allowance for this, and in
consequence of the structure of the alimentary canal has to include in
the food bulky and indigestible materials, such as vegetables. Lastly,
it may be noted that the instinct of appetite in man is largely
aberrant. The widespread results of alcoholism show plainly the
prevalent existence in man of a want of harmony between the instinct for
choosing food and the instinct of preservation.
Far stronger than the social instinct, and far older, is the love of
life and the instinct of self-preservation. Devices for the protection
of life were developed long before the evolution of mankind, and it is
quite certain that animals, even those highest in the scale of life, are
unconscious of the inevitability of death and the ultimate fate of all
living things. This knowledge is a human acquisition. It has long been
recognised that the old attach a higher value to life than do the young.
The instinctive love of life and fear of death are of importance in the
study of human nature, impossible to over-estimate.
The instinctive love of life is preserved in the aged in its strongest
form. I have carefully studied the aged to make certain on this point.
It is a terrible disharmony that the instinctive love of life should
manifest itself so strongly when death is felt to be so near at hand.
Hence the religions of all times have been concerned with the problem of
death.
_III.--Science the Only Remedy for Human Disharmonies_
In religion and in philosophy throughout their whole history we find
attempts to combat the ills arising from the disharmonies of the human
constitution.
Ancient and modern philosophies, like ancient and modern religions, have
concerned themselves with the attempt to remedy the ills of human
existence, and instinctive fear of death has always ensured that great
attention has been paid to the doctrine of immortality.
Science, the youngest daughter of knowledge, has begun to investigate
the great problems affecting humanity. Her first steps, taken along the
lines first clearly laid down by Bacon, were slow and halting. But
medical science has lately made great progress, and has gone very far to
control disease, especially in consequence of the work of Pasteur. It is
said that science has failed because, for instance, tuberculosis
persists, but tuberculosis is propagated not because of the failure of
science, but because of the ignorance and stupidity of the population.
To diminish the spread of tuberculosis, of typhoid fever, of dysentery,
and of many other diseases, it is necessary only to follow the rules of
scientific hygiene without waiting for specific remedies.
Science offers us much hope also when it is directed to the study of old
age and the phenomena which lead to death.
Man, who is the descendant of some anthropoid ape, has inherited a
constitution adapted to an environment very different from that which
now surrounds him. He is possessed of a brain very much more highly
developed than that of his ancestors, and has entered on a new path in
the evolution of the higher organisms. The sudden change in his natural
conditions has brought about a large series of organic disharmonies,
which become more and more acutely felt as he becomes more intelligent
and more sensitive; and thus there has arisen a number of sorrows which
poor humanity has tried to relieve by all the means in its power.
Humanity in its misery has put question after question to science, and
has lost patience at the slowness of the advance of knowledge. It has
declared that the answers already found by science are futile and of
little interest. But science, confident of its methods, has quietly
continued to work. Little by little the answers to some of the
questions that have been set have begun to appear.
Man, because of the fundamental disharmonies in his constitution, does
not develop normally. The earlier phases of his development are passed
through with little trouble; but after maturity greater or lesser
abnormality begins, and ends in old age and death that are premature and
pathological. Is not the goal of existence the accomplishment of a
complete and physiological cycle in which occurs a normal old age,
ending in the loss of the instinct of life and the appearance of the
instinct of death? But before attaining the normal end, coming after the
appearance of the instinct of death, a normal life must be lived; a life
filled all through with the feeling that comes from the accomplishment
of function. Science has been able to tell us that man, the descendant
of animals, has good and evil qualities in his nature, and that his life
is made unhappy by the evil qualities.
But the constitution of man is not immutable, and perhaps it may be
changed for the better. Morality should be based not on human nature in
its existing condition, but on ideal human nature, as it may be in the
future. Before all things, it is necessary to try to amend the evolution
of human life, that is to say, to transform its disharmonies into
harmonies. This task can be undertaken only by science, and to science
the opportunity of accomplishing it must be given. Before it is possible
to reach the goal mankind must be persuaded that science is all-powerful
and that the deeply-rooted existing superstitions are pernicious. It
will be necessary to reform many customs and many institutions that now
seem to rest on enduring foundations. The abandonment of much that is
habitual, and a revolution in the mode of education, will require long
and painful effort. But the conviction that science alone is able to
redress the disharmonies of the human constitution will lead directly to
the improvement of education and to the solidarity of mankind.
The Prolongation of Life
Professor Metchnikoff's volume, on "The Prolongation of Life:
Studies in Optimistic Philosophy," was published in 1907, and is in
some respects the most original of his works. In it he carries much
further the arguments and the studies to which he made brief
allusion in "The Nature of Man," and he lays down certain
principles for the prolongation of life which have been put into
practice by a large number of people during the last two or three
years, and are steadily gaining more attention. Sour milk as an
article of diet appears to have a peculiar value in arresting the
supposed senile changes which are largely due to auto-intoxication
or self-poisoning.
_I.--Senile Debility_
When we study old age in man and the lower animals, we observe certain
features common to both. But often among vertebrates there are found
animals whose bodies withstand the ravages of time much better than that
of man. I think it a fair inference that senility, that precocious
senescence which is one of the greatest sorrows of humanity, is not so
profoundly seated in the constitution of the higher animals as has
generally been supposed. The first facts which we must accept are that
human beings who reach extreme old age may preserve their mental
qualities, notwithstanding serious physical decay, and that certain of
the higher animals can resist the influence of time much longer than is
the case with man under present conditions.
Many theories have been advanced regarding the cause of senility. It is
certain that many parts of the body continue to thrive and grow even in
old age, as, for instance, the nails and hair. But I believe that I have
proved that in many parts of the body, especially the higher elements,
such as nervous and muscular cells, there is a destruction due to the
activity of the white cells of the blood. I have shown also that the
blanching of the hair in old age is due to the activity of these white
cells, which destroy the hair pigment. Progressive muscular debility is
an accompaniment of old age; physical work is seldom given to men over
sixty years of age, as it is notorious that they are less capable of it.
Their muscular movements are feebler, and soon bring on fatigue; their
actions are slow and painful. Even old men whose mental vigour is
unimpaired admit their muscular weakness. The physical correlate of this
condition is an actual atrophy of the muscles, and has for long been
known to observers. I have found that the cause of this atrophy is the
consumption of the muscle fibres by what I call phagocytes, or eating
cells, a certain kind of white blood cells.
In the case of certain diseases we find symptoms, which look like
precocious senility, due to the poison of the disease. It is no mere
analogy to suppose that human senescence is the result of a slow but
chronic poisoning of the organism. Such poisons, if not completely
destroyed or got rid of, weaken the tissues, the functions of which
become altered or enfeebled in which the latter have the advantage. But
we must make further studies before we can answer the question whether
our senescence can be ameliorated.
The duration of the life of animals varies within very wide limits. As a
general rule, small animals do not live so long as large ones, but there
is no absolute relation between size and longevity, since parrots,
ravens, and geese live much longer than many mammals, and than some much
larger birds. Buffon long ago argued that the total duration of life
bore some definite relation to the length of the period of growth, but
further inquiry shows that such a relation cannot be established.
Nevertheless, there is something intrinsic in each kind of animal which
sets a definite limit to the length of years it can attain. The purely
physiological conditions which determine this limit leave room for a
considerable amount of variation in longevity. Duration of life,
therefore, is a character which can be influenced by the environment.
The duration of life in mammals is relatively shorter than in birds, and
in the so-called cold-blooded vertebrates. No indication as to the cause
of this difference can be found elsewhere than in the organs of
digestion. Mammals are the only group of vertebrate animals in which the
large intestine is much developed. This part of the alimentary canal is
not important, for it fulfils no notable digestive function. On the
other hand, it accommodates among the intestinal flora many microbes
which damage health by poisoning the body with their products. Among the
intestinal flora there are many microbes which are inoffensive, but
others are known to have pernicious properties, and auto-intoxication,
or self-poisoning, is the cause of the ill-health which may be traced to
their activity. It is indubitable that the intestinal microbes or their
poisons may reach the system generally, and bring harm to it. I infer
from the facts that the more the digestive tract is charged with
microbes, the more it is a source of harm capable of shortening life. As
the large intestine not only is that part of the digestive tube most
richly charged with microbes, but is relatively more capacious in
mammals than in any other vertebrates, it is a just inference that the
duration of life of mammals has been notably shortened as the result of
chronic poisoning from an abundant intestinal flora.
When we come to study the duration of human life, it is impossible to
accept the view that the high mortality between the ages of seventy and
seventy-five indicates a natural limit to human life. The fact that many
men from seventy to seventy-five years old are well preserved, both
physically and intellectually, makes it impossible to regard that age as
the natural limit of human life. Philosophers such as Plato, poets such
as Goethe and Victor Hugo, artists such as Michael Angelo, Titian, and
Franz Hals, produced some of their most important works when they had
passed what some regard as the limit of life. Moreover, deaths of people
at that age are rarely due to senile debility. Centenarians are really
not rare. In France, for instance, nearly 150 centenarians die every
year, and extreme longevity is not limited to the white races. Women
more frequently become centenarians than men--a fact which supports the
general proposition that male mortality is always greater than that of
the other sex.
It has been noticed that most centenarians have been people who were
poor or in humble circumstances, and whose life has been extremely
simple. It may well be said that great riches do not bring a very long
life. Poverty generally brings with it sobriety, especially in old age,
and sobriety is certainly favourable to long life.
_II.--The Study of Natural Death_
It is surprising to find how little science really knows about death. By
natural death I mean to denote death due to the nature of the organism,
and not to disease. We may ask whether natural death really occurs,
since death so frequently comes by accident or by disease; and certainly
the longevity of many plants is amazing. Such ages as three, four, and
five thousand years are attributed to the baobab at Cape Verd, certain
cypresses, and the sequoias of California. It is plain that among the
lower and higher plants there are cases where natural death does not
exist; and, further, so far as I can ascertain, it looks as if poisons
produced by their own bodies were the cause of natural death among the
higher plants where it does occur.
In the human race cases of what may be called natural death are
extremely rare; the death of old people is usually due to infectious
disease, particularly pneumonia, or to apoplexy. The close analogy
between natural death and sleep supports my view that it is due to an
auto-intoxication of the organism, since it is very probable that sleep
is due to "poisoning" by the products of organic activity.
Although the duration of the life of man is one of the longest amongst
mammals, men find it too short. Ought we to listen to the cry of
humanity that life is too short, and that it will be well to prolong it?
If the question were merely one of prolonging the life of old people,
without modifying old age itself, the answer would be doubtful. It must
be understood, however, that the prolongation of life will be associated
with the preservation of intelligence and of the power to work. When we
have reduced or abolished such causes of precocious senility as
intemperance and disease, it will no longer be necessary to give
pensions at the age of sixty or seventy years. The cost of supporting
the old, instead of increasing, will diminish progressively. We must use
all our endeavors to allow men to complete their normal course of life,
and to make it possible for old men to play their parts as advisers and
judges, endowed with their long experience of life.
From time immemorial suggestions have been made for the prolongation of
life. Many elixirs have been sought and supposed to have been found, but
general hygienic measures have been the most successful in prolonging
life and in lessening the ills of old age. That is the teaching of Sir
Herman Weber, himself of very great age, who advises general hygienic
principles, and especially moderation in all respects. He advises us to
avoid alcohol and other stimulants, as well as narcotics and soothing
drugs. Certainly the prolongation of life which has come to pass in
recent centuries must be attributed to the advance of hygiene; and if
hygiene was able to prolong life when little developed, as was the case
until recently, we may well believe that with our greater knowledge a
much better result will be obtained.
_III.--The Use of Lactic Acid_
The general measures of hygiene directed against infectious diseases
play a part in prolonging the lives of old people; but, in addition to
the microbes which invade the body from outside, there is a rich source
of harm in microbes which inhabit the body. The most important of these
belong to the intestinal flora which is abundant and varied. Now the
attempt to destroy the intestinal microbes by the use of chemical agents
has little chance of success, and the intestine itself may be harmed
more than the microbes. If, however, we observe the new-born child we
find that, when suckled by its mother, its intestinal microbes are very
different and much fewer than if it be fed with cows' milk. I am
strongly convinced that it is advantageous to protect ourselves by
cooking all kinds of food which, like cows' milk, are exposed to the
air. It is well-known that other means--as, for instance, the use of
lactic acid--will prevent food outside the body from going bad. Now as
lactic fermentation serves so well to arrest putrefaction in general,
why should it not be used for the same purpose within the digestive
tube? It has been clearly proved that the microbes which produce lactic
acid can, and do, control the growth of other microbes within the body,
and that the lactic microbe is so much at home in the human body that it
is to be found there several weeks after it has been swallowed.
From time immemorial human beings have absorbed quantities of lactic
microbes by consuming in the uncooked condition substances such as
soured milk, kephir, sauerkraut, or salted cucumbers, which have
undergone lactic fermentation. By these means they have unknowingly
lessened the evil consequences of intestinal putrefaction. The fact that
so many races make soured milk and use it copiously is an excellent
testimony to its usefulness, and critical inquiry shows that longevity,
with few traces of senility, is conspicuous amongst peoples who use sour
milk extensively.
A reader who has little knowledge of such matters may be surprised by my
recommendation to absorb large quantities of microbes, as the general
belief is that microbes are all harmful. This belief, however, is
erroneous. There are many useful microbes, amongst which the lactic
bacilli have an honourable place. If it be true that our precocious and
unhappy old age is due to poisoning of the tissues, the greater part of
the poison coming from the large intestine, inhabited by numberless
microbes, it is clear that agents which arrest intestinal putrefaction
must at the same time postpone and ameliorate old age. This theoretical
view is confirmed by the collection of facts regarding races which live
chiefly on soured milk, and amongst which great ages are common.
_IV.--An Ideal Old Age_
As I have shown in the "Nature of Man," the human constitution as it
exists to-day, being the result of a long evolution and containing a
large animal element, cannot furnish the basis of rational morality. The
conception which has come down from antiquity to modern times, of a
harmonious activity of all the organs, is no longer appropriate to
mankind. Organs which are in course of atrophy must not be re-awakened,
and many natural characters which, perhaps, were useful in the case of
animals, must be made to disappear in men.
Human nature which, like the constitutions of other organisms, is
subject to evolution, must be modified according to a definite ideal.
Just as a gardener or stock-raiser is not content with the existing
nature of the plants and animals with which he is occupied, but modifies
them to suit his purposes, so also the scientific philosopher must not
think of existing human nature as immutable, but must try to modify it
for the advantage of mankind. As bread is the chief article in the human
food, attempts to improve cereals have been made for a very long time,
but in order to obtain results much knowledge is necessary. To modify
the nature of plants, it is necessary to understand them well, and it is
necessary to have an ideal to be aimed at. In the case of mankind the
ideal of human nature, towards which we ought to press, may be formed.
In my opinion this ideal is "orthobiosis"--that is to say, the
development of human life, so that it passes through a long period of
old age in active and vigorous health, leading to a final period in
which there shall be present a sense of satiety of life, and a wish for
death.
Just as we must study the nature of plants before trying to realise our
ideal, so also varied and profound knowledge is the first requisite for
the ideal of moral conduct. It is necessary not only to know the
structure and functions of the human organism, but to have exact ideas
on human life as it is in society. Scientific knowledge is so
indispensable for moral conduct that ignorance must be placed among the
most immoral acts. A mother who rears her child in defiance of good
hygiene, from want of knowledge, is acting immorally towards her
offspring, notwithstanding her feeling of sympathy. And this also is
true of a government which remains in ignorance of the laws which
regulate human life and human society.
If the human race come to adopt the principles of orthobiosis, a
considerable change in the qualities of men of different ages will
follow. Old age will be postponed so much that men of from sixty to
seventy years of age will retain their vigour, and will not require to
ask assistance in the fashion now necessary. On the other hand, young
men of twenty-one years of age will no longer be thought mature or ready
to fulfil functions so difficult as taking a share in public affairs.
The view which I set forth in the "Nature of Man" regarding the danger
which comes from the present interference of young men in political
affairs has since then been confirmed in the most striking fashion.
It is easily intelligible that in the new conditions such modern idols
as universal suffrage, public opinion, and the _referendum_, in which
the ignorant masses are called on to decide questions which demand
varied and profound knowledge, will last no longer than the old idols.
The progress of human knowledge will bring about the replacement of such
institutions by others, in which applied morality will be controlled by
the really competent persons. I permit myself to suppose that in these
times scientific training will be much more general than it is just now,
and that it will occupy the place which it deserves in education and in
life.
Our intelligence informs us that man is capable of much, and, therefore,
we hope that he may be able to modify his own nature and transform his
disharmonies into harmonies. It is only human will that can attain this
ideal.
HUGH MILLER
The Old Red Sandstone
Hugh Miller was born in Cromarty, in the North of Scotland, October
10, 1802. From the time he was seventeen until he was thirty-four,
he worked as a common stone-mason, although devoting his leisure
hours to independent researches in natural history, for which he
formed a taste early in life. He became interested in journalism,
and was editor of the Edinburgh "Witness," when, in 1840, he
published the contents of the volume issued a year later as "The
Old Red Sandstone." The book deals with its author's most
distinctive work, namely, finding fossils that tell much of the
history of the Lower Old Red Sandstone, and fixing in the
geological scale the place to which the larger beds of remains
found in the system belong. Besides being a practical and original
geologist, Miller had a fine imaginative power, which enabled him
to reconstruct the past from its ruinous relics. The fact that he
unfortunately set himself the task of combating the theory of
evolution, which was fast gaining ground in his day, should not
blind us to the high value of his geological experiences. The
results of his observations provide some of the most cogent proofs
of the theory he disputed. Late in life Miller's mind gave way, and
he put an end to his own life on December 24, 1856.
_I.--A Stone-mason's Researches_
My advice to young working men desirous of bettering their
circumstances, and adding to the amount of their enjoyment, is to seek
happiness in study. Learn to make a right use of your eyes; the
commonest things are worth looking at--even stones, weeds, and the most
familiar animals. There are none of the intellectual or moral faculties,
the exercise of which does not lead to enjoyment; hence it is that
happiness bears so little reference to station.
Twenty years ago I made my first acquaintance with a life of labour and
restraint. I was but a slim, loose-jointed boy at the time, fond of the
pretty intangibilities of romance, and of dreaming when broad awake;
and, woful change! I was now going to work in a quarry. I was going to
exchange all my day-dreams for the kind of life in which men toil every
day that they may be enabled to eat, and eat every day that they may be
enabled to toil!
That first day was no very formidable beginning of the course of life I
had so much dreaded. To be sure, my hands were a little sore, and I felt
nearly as much fatigued as if I had been climbing among the rocks; but I
had wrought and been useful, and had yet enjoyed the day fully as much
as usual. I was as light of heart next morning as any of my
brother-workmen. That night, arising out of my employment, I found I had
food enough for thought without once thinking of the unhappiness of a
life of labour.
In the course of the day I picked up a nodular mass of blue limestone,
and laid it open by a stroke of the hammer. Wonderful to relate, it
contained inside a beautifully finished piece of sculpture, one of the
volutes, apparently, of an Ionic capital. Was there another such
curiosity in the whole world? I broke open a few other nodules of
similar appearance, and found that there might be. In one of these there
were what seemed to be scales of fishes and the impressions of a few
minute bivalves, prettily striated; in the centre of another there was
actually a piece of decayed wood.
Of all nature's riddles these seemed to me to be at once the most
interesting and the most difficult to expound. I treasured them
carefully up, and was told by one of the workmen to whom I showed them
that there was a part of the shore, about two miles further to the west,
where curiously shaped stones, somewhat like the heads of
boarding-pikes, were occasionally picked up, and that in his father's
day the country people called them thunderbolts. Our first half-holiday
I employed in visiting the place where the thunderbolts had fallen so
thickly, and found it a richer scene of wonder than I could have
fancied even in my dreams.
My first year of labour came to a close, and I found that the amount of
my happiness had not been less than in the last of my boyhood. My
knowledge had increased in more than the ratio of former seasons; and as
I had acquired the skill of at least the common mechanic, I had fitted
myself for independence.
My curiosity, once fully awakened, remained awake, and my opportunities
of gratifying it have been tolerably ample. I have been an explorer of
caves and ravines, a loiterer along sea-shores, a climber among rocks, a
labourer in quarries. My profession was a wandering one. I remember
passing direct, on one occasion, from the wild western coast of
Ross-shire, where the Old Red Sandstone leans at a high angle against
the prevailing quartz of the district, to where, on the southern skirts
of Midlothian, the Mountain Limestone rises amid the coal. I have
resided one season on a raised beach of the Moray Firth. I have spent
the season immediately following amid the ancient granite and contorted
schists of the central Highlands. In the north I have laid open by
thousands the shells and lignites of the oolite; in the south I have
disinterred from their matrices of stone or of shale the huge reds and
tree ferns of the carboniferous period.
I advise the stone-mason to acquaint himself with geology. Much of his
time must be spent amid the rocks and quarries of widely separated
localities, and so, in the course of a few years he may pass over the
whole geological scale, and this, too, with opportunities of observation
at every stage which can be shared with him by only the gentleman of
fortune who devotes his whole time to study. Nay, in some respects, his
advantages are superior to those of the amateur, for the man whose
employments have to be carried on in the same formation for months,
perhaps years, enjoys better opportunities of arriving at just
conclusions. There are formations which yield their organisms slowly to
the discoverer, and the proofs which establish their place in the
geological scale more tardily still. I was acquainted with the Old Red
Sandstone of Ross and Cromarty for nearly ten years ere I ascertained
that it is richly fossiliferous; I was acquainted with it for nearly ten
years more ere I could assign its fossils to their exact place in the
scale. Nature is vast and knowledge limited, and no individual need
despair of adding to the general fund.
_II.--Bridging Life's Gaps_
"The Old Red Sandstone," says a Scottish geologist in a digest of some
recent geological discoveries, "has hitherto been considered as
remarkably barren of fossils." Only a few years have gone by since men
of no low standing in the science disputed the very existence of this
formation--or system, rather, for it contains at least three distinct
formations. There are some of our British geologists who still regard it
as a sort of debatable tract, entitled to no independent status, a sort
of common which should be divided.
It will be found, however, that this hitherto neglected system yields in
importance to none of the others, whether we take into account its
amazing depth, the great extent to which it is developed both at home
and abroad, the interesting links which it furnishes in the geological
scale, or the vast period of time which it represents. There are
localities in which the depth of the Old Red Sandstone fully equals the
elevation of Mount Etna over the level of the sea, and in which it
contains three distinct groups of organic remains, the one rising in
beautiful progression over the other.
My first statement regarding the system must be much the reverse of the
one just quoted, for the fossils are remarkably numerous and in a state
of high preservation. I have a hundred solid proofs by which to
establish the truth of the assertion within less than a yard of me. Half
my closet walls are covered with the peculiar fossils of the Lower Old
Red Sandstone; and certainly a stranger assemblage of forms has rarely
been grouped together--creatures whose very type is lost, fantastic and
uncouth, which puzzle the naturalist to assign them even to their class;
boat-like animals, furnished with oars and a rudder; fish, plated over,
like the tortoise, above and below, with a strong armour of bone, and
furnished with but one solitary rudder-like fin; other fish with the
membranes of their fins thickly covered with scales; creatures bristling
over with thorns; others glistening in an enamelled coat, as if
beautifully japanned; the tail in every instance among the less
equivocal shapes formed not equally, as in existing fish, on each side
the central vertebral column, but chiefly on the lower side--the column
sending out its diminished vertebræ to the extreme termination of the
fin. All the forms testify of a remote antiquity. The figures on a
Chinese vase or an Egyptian obelisk are scarce more unlike what now
exists in nature than are the fossils of the Lower Old Red Sandstone.
Lamarck, on the strength of a few striking facts which prove that to a
certain extent the instincts of species may be improved and heightened,
has concluded that there is a natural progress from the inferior orders
of being towards the superior, and that the offspring of creatures low
in the scale may belong to a different and nobler species a few thousand
years hence. Never was there a fancy so wild and extravagant. The
principle of adaptation still leaves the vegetable a vegetable, and the
dog a dog. It is true that it is a law of nature that the chain of being
is in some degree a continuous chain, and the various classes of
existence shade into each other. All the animal families have their
connecting links. Geology abounds with creatures of the intermediate
class.
Fishes seem to have been the master existences of two great geological
systems, mayhap of three, ere the age of reptiles began. Now, fishes
differ very much among themselves, some ranking nearly as low as worms,
some nearly as high as reptiles; and we find in the Old Red Sandstone
series of links which are wanting in the present creation, and the
absence of which occasions a wide gap between the two grand divisions of
fishes, the bony and the cartilaginous.
Of all the organisms of the system one of the most extraordinary is the
pterichthys, or winged fish, which the writer had the pleasure of
introducing to the acquaintance of geologists. Had Lamarck been the
discoverer he would unquestionably have held that he had caught a fish
almost in the act of wishing itself into a bird. There are wings which
want only feathers, a body which seems to have been as well adapted for
passing through the air as through water, and a tail with which to
steer.
My first idea regarding it was that I had discovered a connecting
link-between the tortoise and the fish. I submitted some of my specimens
to Mr. Murchison, and they furnished him with additional data by which
to construct the calculations he was then making respecting fossils, and
they added a new and very singular link to the chain of existence in its
relation to human knowledge. Agassiz confirmed the conclusions of
Murchison in almost every particular, deciding at once that the creature
must have been a fish.
Next to the pterichthys of the Lower Old Red Sandstone I shall place its
contemporary the coccosteus of Agassiz--a fish which in some respects
must have resembled it. Both were covered with an armour of thickly
tubercled bony plates, and both furnished with a vertebrated tail. The
coccosteus seems to have been most abundant. Another of the families of
the ichthyolites of the Old Red Sandstone--the cephalaspis--seems
almost to constitute a connecting link between fishes and crustaceans.
In the present creation fishes are either osseous or cartilaginous, that
is, with bony skeletons, or with a framework of elastic,
semi-transparent animal matter, like the shark; and the ichthyolites of
the Old Red Sandstone unite these characteristics, resembling in some
respects the osseous and in others the cartilaginous tribes. Agassiz at
once confirmed my suspicion that the ichthyolites of the Old Red
Sandstone were intermediate. Though it required skill to determine the
place of the pterichthys and coccosteus there could be no mistaking the
osteolepis--it must have been a fish, and a handsome one, too. But while
its head resembled the heads of the bony fishes, its tail differed in no
respects from the tails of the cartilaginous ones. And so through the
discovery of extinct species the gaps between existing species have been
bridged.
_III.--Place-Fixing in the Dim Past_
The next step was to fix the exact place of the ichthyolites in the
geological scale, and this I was enabled to do by finding a large and
complete bed _in situ_. Its true place is a little more than a hundred
feet above the top, and not much more than a hundred yards above the
base of the great conglomerate.
The Old Red Sandstone in Scotland and in England has its lower, middle,
and upper groups--three distinct formations. As the pterichthys and
coccosteus are the characteristic ichthyolites of the Lower Old Red
formation, so the cephalaspis distinguishes the middle or coronstone
division of the system in England. When we pass to the upper formation,
we find the holoptychius the most characteristic fossil.
These fossils are found in a degree of entireness which depends less on
their age than on the nature of the rock in which they occur. Limestone
is the preserving salt of the geological world, and the conservative
qualities of the shales and stratified clays of the Lower Old Red
Sandstone are not much inferior to limestone itself; while in the Upper
Old Red the beds of consolidated sand are much less conservative of
organic remains. The older fossils, therefore, can be described almost
as minutely as the existence of the present creation, whereas the newer
fossils exist, except in a few rare cases, as fragments, and demand the
powers of a Cuvier or an Agassiz to restore them to their original
combinations. On the other hand, while the organisms of the Lower Old
Red are numerous and well preserved, those of the Upper Old Red are much
greater in individual size. In short, the fish of the lower ocean must
have ranged in size between a stickleback and a cod; whereas some of the
fish of the ocean of the Upper Sandstone were covered with scales as
large as oyster shells, and were armed with teeth that rivalled in size
those of the crocodile.
_IV.--Fish as Nature's Last Word_
I will now attempt to present to the reader the Old Red Sandstone as it
existed in time--during the succeeding periods of its formation, and
when its existences lived and moved as the denizens of primeval oceans.
We pass from the cemetery with its heaps of bones to the ancient city
full of life and animation in all its streets and dwellings.
Before we commence our picture, two great geological periods have come
to their close, and the floor of the widely spread ocean is occupied to
the depth of many thousand feet by the remains of bygone existences. The
rocks of these two earlier periods are those of the Cambrian and
Silurian groups. The lower--Cambrian, representative of the first
glimmering twilight of being--must be regarded as a period of
uncertainty. It remains for future discoverers to determine regarding
the shapes of life that burrowed in its ooze or careered through the
incumbent waters.
There is less doubt respecting the existences of the Silurian rocks.
Four distinct platforms of being range in it, the one over the other,
like the stories of a building. Life abounded on all these platforms,
and in shapes the most wonderful. In the period of the Upper Silurian
fish, properly so called, and of a very perfect organisation, had taken
precedence of the crustacean. These most ancient beings of their class
were cartilaginous fishes, and they appear to have been introduced by
myriads. Such are the remains of what seem to have been the first
vertebrata.
The history of the period represented by the Old Red Sandstone seems, in
what now forms the northern half of Scotland, to have opened amid
confusion and turmoil. The finely laminated Tilestones of England were
deposited evidently in a calm sea. During the contemporary period the
space which now includes Orkney, Lochness, Dingwall, Gamrie, and many a
thousand square miles besides, was the scene of a shallow ocean,
perplexed by powerful currents and agitated by waves. A vast stratum of
water-rolled pebbles, varying in depth from a hundred feet to a hundred
yards, remains, in a thousand different localities, to testify to the
disturbing agencies of this time of commotion, though it is difficult to
conceive how the bottom of any sea could have been so violently and
equally agitated for so greatly extended a space.
The period of this shallow and stormy ocean passed, and the bottom,
composed of the identical conglomerate which now forms the summit of
some of our loftiest mountains, sank to a depth so profound as to be
little affected by tides and tempests. During this second period there
took place a vast deposit of coarse sandstone strata, and the subsidence
continued until fully ninety feet had overlaid the conglomerate in
waters perfectly undisturbed. And here we find the first proof that this
ancient ocean literally swarmed with life--that its bottom was covered
with miniature forests of algae, and its waters darkened by immense
shoals of fish. I have seen the ichthyolite bed where they were as
thickly covered with fossil remains as I have ever seen a fishing-bank
covered with herrings.
At this period some terrible catastrophe involved in sudden destruction
the fish of an area at least a hundred miles from boundary to boundary,
perhaps much more. The same platform in Orkney as in Cromarty is strewn
thick with remains which exhibit unequivocally the marks of violent
death. In what could it have originated? By what quiet but potent agency
of destruction could the innumerable existences of an area perhaps ten
thousand miles in extent be annihilated at once, and yet the medium in
which they lived be left undisturbed by its operations? The thought has
often struck me that calcined lime, cast out as ashes from some distant
crater and carried by the winds, might have been the cause of the widely
spread destruction to which the fossil organisms testify. I have seen
the fish of a small trouting stream, over which a bridge was in the
course of building, destroyed in a single hour, for a full mile below
the erection, by a few troughfuls of lime that fell into the water when
the centring was removed.
The period of death passed, and over the innumerable dead there settled
a soft muddy sediment. For an unknown space of time, represented in the
formation by a deposit about fifty feet in thickness, the waters of the
depopulated area seem to have remained devoid of life. A few scales and
plates then begin to appear. The fish that had existed outside the chasm
seem to have gradually gained upon it as their numbers increased.
The work of deposition went on and sandstone was overlaid by stratified
clay. This upper bed had also its organisms, but the circumstances were
less favourable to the preservation of entire ichthyolites than those in
which the organisms were wrapped up in their stony coverings. Age
followed age, generations were entombed in ever-growing depositions.
Vast periods passed, and it seemed as if the power of the Creator had
reached its extreme limit when fishes had been called into existence,
and our planet was destined to be the dwelling-place of no nobler
inhabitants.
The curtain rises, and the scene is new. The myriads of the lower
formation have disappeared, and we are surrounded on an upper platform
by the existences of a later creation. Shoals of cephalaspides,
feathered with fins, sweep past. We see the distant gleam of scales,
that some of the coats glitter with enamel, that others bristle over
with minute thorny points. A huge crustacean, of uncouth proportions,
stalks over the weedy bottoms, or burrows in the hollows of the banks.
Ages and centuries pass--who can sum up their number?--for the depth of
this middle formation greatly exceeds that of the other two.
The curtain rises. A last day had at length come to the period of the
middle formation, and in an ocean roughened by waves and agitated by
currents we find new races of existences. We may mark the clumsy bulk of
the Holoptychius conspicuous in the group. The shark family have their
representative as before; a new variety of the pterichthys spreads out
its spear-like wings at every alarm, like its predecessor of the lower
formation. Fish still remained the lords of creation, and their bulk, at
least, had become immensely more great. We began with an age of dwarfs,
we end with an age of giants, which is carried on into the lower coal
measures. We pursue our history no further?
Has the last scene in the series arisen? Cuvier asked the question,
hesitated, and then decided in the negative, for he was too intimately
acquainted with the works of the Creator to think of limiting His power,
and he could anticipate a coming period in which man would have to
resign his post of honour to some nobler and wiser creature, the monarch
of a better and happier world.
SIR ISAAC NEWTON
Principia
Sir Isaac Newton was born at Woolsthorpe, Lincolnshire, England,
Dec. 25, 1642, the son of a small landed proprietor. For the famous
episode of the falling apple, Voltaire, who admirably explained his
system for his countrymen, is responsible. It was in 1680 that
Newton discovered how to calculate the orbit of a body moving under
a central force, and showed that if the force varied as the inverse
square of the distance, the orbit would be an ellipse with the
centre of force in one focus. The great discovery, which made the
writing of his "Philosophiæ Naturalis Principia Mathematica"
possible, was that the attraction between two spheres is the same
as it would be if we supposed each sphere condensed to a point at
its centre. The book was published as a whole in 1687. Of its
author it was said by Lagrange that not only was he the greatest
genius that ever existed, but also the most fortunate, "for we
cannot find more than once a system of the world to establish."
Newton died on March 20, 1727.
Our design (writes Newton in his preface) not respecting arts but
philosophy, and our subject not manual but natural powers, we consider
those things which relate to gravity, levity, elastic force, the
resistance of fluids and the like forces, whether attractive or
impulsive; and, therefore, we offer this work as the mathematical
principles of philosophy, for all the difficulty of philosophy seems to
consist in this--from the phenomena of motions to investigate the forces
of nature, and from these forces to demonstrate the other phenomena, and
to this end the general propositions in the first and second book are
directed. In the third book, we give an example of this in the
explication of the system of the world; for by the propositions
mathematically demonstrated in the former books, we in the third derive
from the celestial phenomena the forces of gravity with which bodies
tend to the sun and the several planets. Then from these forces, by
other propositions which are also mathematical, we deduce the motions of
the planets, the comets, the moon, and the sea.
Upon this subject I had (he says) composed the third book in a popular
method, that it might be read by many, but afterward, considering that
such as had not sufficiently entered into the principles could not
easily discern the strength of the consequences, nor lay aside the
prejudices to which they had been many years accustomed, therefore, to
prevent the disputes which might be raised upon such accounts, I chose
to reduce the substance of this book into the form of Propositions (in
the mathematical way). So that this third book is composed both "in
popular method" and in the form of mathematical propositions.
_Books I and II_
The principle of universal gravitation, namely, "That every particle of
matter is attracted by or gravitates to every other particle of matter
with a force inversely proportional to the squares of their distances,"
is the discovery which characterises the "Principia." This principle the
author deduced from the motion of the moon and the three laws of Kepler;
and these laws in turn Newton, by his greater law, demonstrated to be
true.
From the first law of Kepler, namely, the proportionality of the areas
to the times of their description, Newton inferred that the force which
retained the planet in its orbit was always directed to the sun. From
the second, namely, that every planet moves in an ellipse with the sun
as one of foci, he drew the more general inference that the force by
which the planet moves round that focus varies inversely as the square
of its distance therefrom. He demonstrated that a planet acted upon by
such a force could not move in any other curve than a conic section; and
he showed when the moving body would describe a circular, an elliptical,
a parabolic, or hyperbolic orbit. He demonstrated, too, that this force
or attracting, gravitating power resided in even the least particle; but
that in spherical masses it operates as if confined to their centres, so
that one sphere or body will act upon another sphere or body with a
force directly proportional to the quantity of matter and inversely as
the square of the distance between their centres, and that their
velocities of mutual approach will be in the inverse ratio of their
quantities of matter. Thus he outlined the universal law.
_The System of the World_
It was the ancient opinion of not a few (writes Newton in Book III.) in
the earliest ages of philosophy that the fixed stars stood immovable in
the highest parts of the world; that under the fixed stars the planets
were carried about the sun; that the earth, as one of the planets,
described an annual course about the sun, while, by a diurnal motion, it
was in the meantime revolved about its own axis; and that the sun, as
the common fire which served to warm the whole, was fixed in the centre
of the universe. It was from the Egyptians that the Greeks derived their
first, as well as their soundest notions of philosophy. It is not to be
denied that Anaxagoras, Democritus and others would have it that the
earth possessed the centre of the world, but it was agreed on both sides
that the motions of the celestial bodies were performed in spaces
altogether free and void of resistance. The whim of solid orbs was[1] of
later date, introduced by Endoxus, Calippus and Aristotle, when the
ancient philosophy began to decline.
As it was the unavoidable consequence of the hypothesis of solid orbs
while it prevailed that the comets must be thrust down below the moon,
so no sooner had the late observations of astronomers restored the
comets to their ancient places in the higher heavens than these
celestial spaces were at once cleared of the encumbrance of solid orbs,
which by these observations were broken to pieces and discarded for
ever.
Whence it was that the planets came to be retained within any certain
bounds in these free spaces, and to be drawn off from the rectilinear
courses, which, left to themselves, they should have pursued, into
regular revolutions in curvilinear orbits, are questions which we do not
know how the ancients explained; and probably it was to give some sort
of satisfaction to this difficulty that solid orbs were introduced.
The later philosophers pretend to account for it either by the action of
certain vortices, as Kepler and Descartes, or by some other principle of
impulse or attraction, for it is most certain that these effects must
proceed from the action of some force or other. This we will call by the
general name of a centripetal force, as it is a force which is directed
to some centre; and, as it regards more particularly a body in that
centre, we call it circum-solar, circum-terrestrial, circum-jovial.
_Centre-Seeking Forces_
That by means of centripetal forces the planets may be retained in
certain orbits we may easily understand if we consider the motions of
projectiles, for a stone projected is by the pressure of its own weight
forced out of the rectilinear path, which, by the projection alone, it
should have pursued, and made to describe a curve line in the air; and
through that crooked way is at last brought down to the ground, and the
greater the velocity is with which it is projected the further it goes
before it falls to earth. We can, therefore, suppose the velocity to be
so increased that it would describe an arc of 1, 2, 5, 10, 100, 1,000
miles before it arrived at the earth, till, at last, exceeding the
limits of the earth, it should pass quite by it without touching it.
And because the celestial motions are scarcely retarded by the little or
no resistance of the spaces in which they are performed, to keep up the
parity of cases, let us suppose either that there is no air about the
earth or, at least, that it is endowed with little or no power of
resisting.
And since the areas which by this motion it describes by a radius drawn
to the centre of the earth have previously been shown to be proportional
to the times in which they are described, its velocity when it returns
to the point from which it started will be no less than at first; and,
retaining the same velocity, it will describe the same curve over and
over by the same law.
But if we now imagine bodies to be projected in the directions of lines
parallel to the horizon from greater heights, as from 5, 10, 100, 1,000
or more miles, or, rather, as many semi-diameters of the earth, those
bodies, according to their different velocity and the different force of
gravity in different heights, will describe arcs either concentric with
the earth or variously eccentric, and go on revolving through the
heavens in those trajectories just as the planets do in their orbs.
As when a stone is projected obliquely, the perpetual deflection thereof
towards the earth is a proof of its gravitation to the earth no less
certain than its direct descent when suffered to fall freely from rest,
so the deviation of bodies moving in free spaces from rectilinear paths
and perpetual deflection therefrom towards any place, is a sure
indication of the existence of some force which from all quarters impels
those bodies towards that place.
That there are centripetal forces actually directed to the bodies of
the sun, of the earth, and other planets, I thus infer.
The moon revolves about our earth, and by radii drawn to its centre
describes areas nearly proportional to the times in which they are
described, as is evident from its velocity compared with its apparent
diameter; for its motion is slower when its diameter is less (and
therefore its distance greater), and its motion is swifter when its
diameter is greater.
The revolutions of the satellites of Jupiter about the planet are more
regular; for they describe circles concentric with Jupiter by equable
motions, as exactly as our senses can distinguish.
And so the satellites of Saturn are revolved about this planet with
motions nearly circular and equable, scarcely disturbed by any
eccentricity hitherto observed.
That Venus and Mercury are revolved about the sun is demonstrable from
their moon-like appearances. And Venus, with a motion almost uniform,
describes an orb nearly circular and concentric with the sun. But
Mercury, with a more eccentric motion, makes remarkable approaches to
the sun and goes off again by turns; but it is always swifter as it is
near to the sun, and therefore by a radius drawn to the sun still
describes areas proportional to the times.
Lastly, that the earth describes about the sun, or the sun about the
earth, by a radius from one to the other, areas exactly proportional to
the times is demonstrable from the apparent diameter of the sun compared
with its apparent motion.
These are astronomical experiments; from which it follows that there are
centripetal forces actually directed to the centres of the earth, of
Jupiter, of Saturn, and of the sun.[2]
That these forces decrease in the duplicate proportion of the distances
from the centre of every planet appears by Cor. vi., Prop. iv., Book
I.[3] for the periodic times of the satellites of Jupiter are one to
another in the sesquiplicate proportion of their distances from the
centre of this planet. Cassini assures us that the same proportion is
observed in the circum-Saturnal planets. In the circum-solar planets
Mercury and Venus, the same proportional holds with great accuracy.
That Mars is revolved about the sun is demonstrated from the phases
which it shows and the proportion of its apparent diameters; for from
its appearing full near conjunction with the sun and gibbous in its
quadratures,[4] it is certain that it travels round the sun. And since
its diameter appears about five times greater when in opposition to the
sun than when in conjunction therewith, and its distance from the earth
is reciprocally as its apparent diameter, that distance will be about
five times less when in opposition to than when in conjunction with the
sun; but in both cases its distance from the sun will be nearly about
the same with the distance which is inferred from its gibbous appearance
in the quadratures. And as it encompasses the sun at almost equal
distances, but in respect of the earth is very unequally distant, so by
radii drawn to the sun it describes areas nearly uniform; but by radii
drawn to the earth it is sometimes swift, sometimes stationary, and
sometimes retrograde.
That Jupiter in a higher orbit than Mars is likewise revolved about the
sun with a motion nearly equable as well in distance as in the areas
described, I infer from Mr. Flamsted's observations of the eclipses of
the innermost satellite; and the same thing may be concluded of Saturn
from his satellite by the observations of Mr. Huyghens and Mr. Halley.
If Jupiter was viewed from the sun it would never appear retrograde or
stationary, as it is seen sometimes from the earth, but always to go
forward with a motion nearly uniform. And from the very great inequality
of its apparent geocentric motion we infer--as it has been previously
shown that we may infer--that the force by which Jupiter is turned out
of a rectilinear course and made to revolve in an orbit is not directed
to the centre of the earth. And the same argument holds good in Mars and
in Saturn. Another centre of these forces is, therefore, to be looked
for, about which the areas described by radii intervening may be
equable; and that this is the sun, we have proved already in Mars and
Saturn nearly, but accurately enough in Jupiter.
The distances of the planets from the sun come out the same whether,
with Tycho, we place the earth in the centre of the system, or the sun
with Copernicus; and we have already proved that, these distances are
true in Jupiter. Kepler and Bullialdus have with great care determined
the distances of the planets from the sun, and hence it is that their
tables agree best with the heavens. And in all the planets, in Jupiter
and Mars, in Saturn and the earth, as well as in Venus and Mercury, the
cubes of their distances are as the squares of their periodic times;
and, therefore, the centripetal circum-solar force throughout all the
planetary regions decreases in the duplicate proportion of the distances
from the sun. Neglecting those little fractions which may have arisen
from insensible errors of observation, we shall always find the said
proportion to hold exactly; for the distances of Saturn, Jupiter, Mars,
the Earth, Venus, and Mercury from the sun, drawn from the observations
of astronomers, are (Kepler) as the numbers 951,000, 519,650, 152,350,
100,000, 70,000, 38,806; or (Bullialdus) as the numbers 954,198,
522,520, 152,350, 100,000, 72,398, 38,585; and from the periodic times
they come out 953,806, 520,116, 152,399, 100,000, 72,333, 38,710. Their
distances, according to Kepler and Bullialdus, scarcely differ by any
sensible quantity, and where they differ most the differences drawn from
the periodic times fall in between them.
_Earth as a Centre_
That the circum-terrestrial force likewise decreases in the duplicate
proportion of the distances, I infer thus:
The mean distance of the moon from the centre of the earth is, we may
assume, sixty semi-diameters of the earth; and its periodic time in
respect of the fixed stars 27 days 7 hr. 43 min. Now, it has been shown
in a previous book that a body revolved in our air, near the surface of
the earth supposed at rest, by means of a centripetal force which should
be to the same force at the distance of the moon in the reciprocal
duplicate proportion of the distances from the centre of the earth, that
is, as 3,600 to 1, would (secluding the resistance of the air) complete
a revolution in 1 hr. 24 min. 27 sec.
Suppose the circumference of the earth to be 123,249,600 Paris feet,
then the same body deprived of its circular motion and falling by the
impulse of the same centripetal force as before would in one second of
time describe 15-1/12 Paris feet. This we infer by a calculus formed
upon Prop. xxxvi. ("To determine the times of the descent of a body
falling from a given place"), and it agrees with the results of Mr.
Huyghens's experiments of pendulums, by which he demonstrated that
bodies falling by all the centripetal force with which (of whatever
nature it is) they are impelled near the surface of the earth do in one
second of time describe 15-1/12 Paris feet.
But if the earth is supposed to move, the earth and moon together will
be revolved about their common centre of gravity. And the moon (by Prop,
lx.) will in the same periodic time, 27 days 7 hr. 43 min., with the
same circum-terrestrial force diminished in the duplicate proportion of
the distance, describe an orbit whose semi-diameter is to the
semi-diameter of the former orbit, that is, to the sixty semi-diameters
of the earth, as the sum of both the bodies of the earth and moon to the
first of two mean proportionals between this sum and the body of the
earth; that is, if we suppose the moon (on account of its mean apparent
diameter 31-1/2 min.) to be about 1/42 of the earth, as 43 to (42 +
42^2)^1/3 or as about 128 to 127. And, therefore, the semi-diameter of
the orbit--that is, the distance of the centres of the moon and
earth--will in this case be 60-1/2 semi-diameters of the earth, almost
the same with that assigned by Copernicus; and, therefore, the duplicate
proportion of the decrement of the force holds good in this distance.
(The action of the sun is here disregarded as inconsiderable.)
This proportion of the decrement of the forces is confirmed from the
eccentricity of the planets, and the very slow motion of their apsides;
for in no other proportion, it has been established, could the
circum-solar planets once in every revolution descend to their least,
and once ascend to their greatest distance from the sun, and the places
of those distances remain immovable. A small error from the duplicate
proportion would produce a motion of the apsides considerable in every
revolution, but in many enormous.
_The Tides_
While the planets are thus revolved in orbits about remote centres, in
the meantime they make their several rotations about their proper axes:
the sun in 26 days, Jupiter in 9 hr. 56 min., Mars in 24-2/3 hr., Venus
in 23 hr., and in like manner is the moon revolved about its axis in 27
days 7 hr. 43 min.; so that this diurnal motion is equal to the mean
motion of the moon in its orbit; upon which account the same face of the
moon always respects the centre about which this mean motion is
performed--that is, the exterior focus of the moon's orbit nearly.
By reason of the diurnal revolutions of the planets the matter which
they contain endeavours to recede from the axis of this motion; and
hence the fluid parts, rising higher towards the equator than about the
poles, would lay the solid parts about the equator under water if those
parts did not rise also; upon which account the planets are something
thicker about the equator than about the poles.
And from the diurnal motion and the attractions of the sun and moon our
sea ought twice to rise and twice to fall every day, as well lunar as
solar. But the two motions which the two luminaries raise will not
appear distinguished but will make a certain mixed motion. In the
conjunction or opposition of the luminaries their forces will be
conjoined and bring on the greatest flood and ebb. In the quadratures
the sun will raise the waters which the moon depresseth and depress the
waters which the moon raiseth; and from the difference of their forces
the smallest of all tides will follow.
But the effects of the lumniaries depend upon their distances from the
earth, for when they are less distant their effects are greater and when
more distant their effects are less, and that in the triplicate
proportion of their apparent diameters. Therefore it is that the sun in
winter time, being then in its perigee, has a greater effect, whether
added to or subtracted from that of the moon, than in the summer season,
and every month the moon, while in the perigee raiseth higher tides than
at the distance of fifteen days before or after when it is in its
apogee.
The fixed stars being at such vast distances from one another, can
neither attract each other sensibly nor be attracted by our sun.
_Comets_
There are three hypotheses about comets. For some will have it that they
are generated and perish as often as they appear and vanish; others that
they come from the regions of the fixed stars, and are near by us in
their passage through the sytem of our planets; and, lastly, others that
they are bodies perpetually revolving about the sun in very eccentric
orbits.
In the first case, the comets, according to their different velocities,
will move in conic sections of all sorts; in the second they will
describe hyperbolas; and in either of the two will frequent
indifferently all quarters of the heavens, as well those about the poles
as those towards the ecliptic; in the third their motions will be
performed in eclipses very eccentric and very nearly approaching to
parabolas. But (if the law of the planets is observed) their orbits will
not much decline from the plane of the ecliptic; and, so far as I could
hitherto observe, the third case obtains; for the comets do indeed
chiefly frequent the zodiac, and scarcely ever attain to a heliocentric
latitude of 40 degrees. And that they move in orbits very nearly
parabolical, I infer from their velocity; for the velocity with which a
parabola is described is everywhere to the velocity with which a comet
or planet may be revolved about the sun in a circle at the same
distance in the subduplicate ratio of 2 to 1; and, by my computation,
the velocity of comets is found to be much about the same. I examined
the thing by inferring nearly the velocities from the distances, and the
distances both from the parallaxes and the phenomena of the tails, and
never found the errors of excess or defect in the velocities greater
than what might have arisen from the errors in the distances collected
after that manner.
SIR RICHARD OWEN
Anatomy of Vertebrates
Sir Richard Owen, the great naturalist, was born July 20, 1804, at
Lancaster, England, and received his early education at the grammar
school of that town. Thence he went to Edinburgh University. In
1826 he was admitted a member of the English College of Surgeons,
and in 1829 was lecturing at St. Bartholomew's Hospital, London,
where he had completed his studies. His "Memoir on the Pearly
Nautillus," published in 1832, placed him, says Huxley, "at a bound
in the front rank of anatomical monographers," and for sixty-two
years the flow of his contributions to scientific literature never
ceased. In 1856 he was appointed to take charge of the natural
history departments of the British Museum, and before long set
forth views as to the inadequacy of the existing accommodation,
which led ultimately to the foundation of the buildings now devoted
to this purpose in South Kensington. Owen died on December 18,
1892. His great book, "Comparative Anatomy and Physiology of the
Vertebrates," was completed in 1868, and since Cuvier's
"Comparative Anatomy," is the most monumental treatise on the
subject by any one man. Although much of the classification adopted
by Owen has not been accepted by other zoologists, yet the work
contains an immense amount of information, most of which was gained
from Owen's own personal observations and dissections.
_I.--Biological Questions of 1830_
At the close of my studies at the Jardin des Plantes, Paris, in 1831, I
returned strongly moved to lines of research bearing upon the then
prevailing phases of thought on some biological questions.
The great master in whose dissecting rooms I was privileged to work held
that species were not permanent as a fact established inductively on a
wide basis of observation, by which comparative osteology had been
created. Camper and Hunter suspected the species might be transitory;
but Cuvier, in defining the characters of his anaplotherium and
palæotherium, etc., proved the fact. Of the relation of past to present
species, Cuvier had not an adequate basis for a decided opinion.
Observation of changes in the relative position of land and sea
suggested to him one condition of the advent of new species on an island
or continent where old species had died out. This view he illustrates by
a hypothetical case of such succession, but expressly states: "I do not
assert that a new creation was necessary to produce the species now
existing, but only that they did not exist in the same regions, and must
have come from elsewhere." Geoffrey Saint Hilaire opposed to Cuvier's
inductive treatment of the question the following expression of belief:
"I have no doubt that existing animals are directly descended from the
animals of the antediluvian world," but added, "it is my belief that the
season has not yet arrived for a really satisfying knowledge of
geology."
The main collateral questions argued in their debates appeared to me to
be the following:
Unity of plan or final purpose, as a governing condition of organic
development?
Series of species, uninterrupted or broken by intervals?
Extinction, cataclysmal or regulated?
Development, by epigenesis or evolution?
Primary life, by miracle or secondary law?
Cuvier held the work of organisation to be guided and governed by final
purpose or adaptation. Geoffrey denied the evidence of design and
contended for the principle which he called "unity of composition," as
the law of organisation. Most of his illustrations were open to the
demonstration of inaccuracy; and the language by which disciples of the
kindred school of Schelling illustrated in the animal structure the
transcendental idea of the whole in every part seemed little better than
mystical jargon. With Cuvier, answerable parts occurred in the
zoological scale because they had to perform similar functions.
As, however, my observations and comparisons accumulated, they enforced
a reconsideration of Cuvier's conclusions. To demonstrate the evidence
of the community of organisation I found the artifice of an archetype
vertebrate animal essential; and from the demonstration of its
principle, which I then satisfied myself was associated with and
dominated by that of "adaptation to purpose," the step was inevitable to
the conception of the operation of a secondary cause of the entire
series of species, such cause being the servant of predetermining
intelligent will.
But besides "derivation" or "filiation" another principle influencing
organisation became recognisable, to which I gave the name of
"irrelative repetition," or "vegetative repetition." The demonstrated
constitution of the vertebrate endoskeleton as a series of essentially
similar segments appeared to me to illustrate the law of irrelative
repetition.
These results of inductive research swayed me in rejecting direct or
miraculous creation, and in recognising a "natural law or secondary
cause" as operative in the production of species "in orderly succession
and progression."
_II.--Succession of Species, Broken or Linked?_
To the hypothesis that existing are modifications of extinct species,
Cuvier replied that traces of modification were due from the fossil
world. "You ought," he said, "to be able to show the intermediate forms
between the palæotherium and existing hoofed quadrupeds."
The progress of palæontology since 1830 has brought to light many
missing links unknown to the founder of the science. The discovery of
the remains of the hipparion supplied one of the links required by
Cuvier, and it is significant that the remains of such three-toed horses
are found only in deposits of that tertiary period which intervene
between the older palæotherian one and the newer strata in which the
modern horse first appears to have lost its lateral hooflets.
The molar series of the horse includes six large complex grinders
individually recognisable by developmental characters. The
representative of the first premolar is minute and soon shod. Its
homologue in palæotherium is functionally developed and retained, that
type-dentition being adhered to. In hipparion this tooth is smaller than
in palæotherium, but functional and permanent. The transitory and
singularly small and simple denticle in the horse exemplifies the
rudiment of an ancestral structure in the same degree as do the hoofless
splint-bones; just as the spurious hoofs dangling therefrom in hipparion
are retained rudiments of the functionally developed lateral hoofs in
the broader foot of palæotherium.
Other missing links of this series of species have also been supplied.
How then is the origin of these intermediate gradations to be
interpreted? If the alternative--species by miracle or by law--be
applied to palæotherium, paloplotherium, anchitherium, hipparion, equus,
I accept the latter without misgiving, and recognise such law as
continuously operative throughout tertiary time.
In respect to its law of operation we may suppose Lamarck to say, "as
the surface of the earth consolidated, the larger and more produced
mid-hoof of the old three-toed pachyderius took a greater share in
sustaining the animal's weight; and more blood being required to meet
the greater demand of the more active mid-toe, it grew; whilst, the
side-toes, losing their share of nourishment and becoming more and more
withdrawn from use, shrank"--and so on. Mr. Darwin, I conceive, would
modify this by saying that some individuals of palæotherium happening to
be born with a larger and longer middle toe, and with shorter and
smaller side-toes, such variety was better adapted to prevailing altered
conditions of the earth's surface than the parental form; and so on,
until finally the extreme equine modifications of foot came to be
"naturally selected." But the hypothesis of appetency and volition, as
of natural selection, are less applicable, less intelligible, in
connection with the changes in the teeth.
I must further observe that to say the palæotherium has graduated into
equus by "natural selection" is an explanation of the process of the
same kind and value as that by which the secretion of bile was
attributed to the "appetency" of the liver for the elements of bile.
One's surprise is that such explanatory devices should not have died out
with the "archeus faber," the "nisus formations," and other
self-deceiving, world-beguiling simulacra of science, with the last
century; and that a resuscitation should have had any success in the
present.
What, then, are the facts on which any reasonable or intelligible
conception can be formed of the mode of operation of the derivative law
exemplified in the series linking on palæotherium to equus? A very
significant one is the following. A modern horse occasionally comes into
the world with the supplementary ancestral hoofs. From Valerius Maximus,
who attributes the variety to Bucephalus downwards, such "polydactyle"
horses have been noted as monsters and marvels. In one of the latest
examples, the inner splint-bone, answering to the second metacarpal of
the pentadactyle foot, supported phalanges and a terminal hoof
resembling the corresponding one in hipparion. And the pairing of horses
with the meterpodials bearing, according to type, phalanges and hoofs
might restore the race of hipparions.
Now, the fact suggesting such possibility teaches that the change would
be sudden and considerable; it opposes the idea that species are
transmuted by minute and slow degrees. It also shows that a species
might originate independently of the operation of any external
influence; that change of structure would precede that of use and
habit; that appetency, impulse, ambient medium, fortuitous fitness of
surrounding circumstances, or a personified "selecting nature" would
have had no share in the transmutative act.
Thus I have been led to recognise species as exemplifying the continuous
operation of natural law, or secondary cause; and that not only
successively but progressively; "from the first embodiment of the
vertebrate idea under its old ichthyic vestment until it became arrayed
in the glorious garb of the human form."
_III.--Extinction--Cataclysmal or Regulated_
If the species of palæothere, paloplothere, anchithere, hipparion, and
horse be severally deemed due to remotely and successively repeated acts
of creation; the successive going out of such species must have been as
miraculous as their coming in. Accordingly, in Cuvier's "Discourse on
Revolutions of the Earth's Surface" we have a section of "Proofs that
these revolutions have been numerous," and another of "Proofs that these
revolutions have been sudden." But as the discoveries of palæontologists
have supplied the links between the species held to have perished by the
cataclysms, so each successive parcel of geological truth has tended to
dissipate the belief in the unusually sudden and violent nature of the
changes recognisable in the earth's surface. In specially directing my
attention to this moot point, whilst engaged in investigations of fossil
remains, I was led to recognise one cause of extinction as being due to
defeat in the contest which the individual of each species had to
maintain against the surrounding agencies which might militate against
its existence. This principle has received a large and most instructive
accession of illustrations from the labours of Charles Darwin; but he
aims to apply it not only to the extinction but to the origin of
species.
Although I fail to recognise proof of the latter bearing of the battle
of life, the concurrence of so much evidence in favour of extinction by
law is, in like measure, corroborative of the truth of the ascription of
the origin of species to a secondary cause.
What spectacle can be more beautiful than that of the inhabitants of the
calm expanse of water of an atoll encircled by its ring of coral rock!
Leaving locomotive frequenters of the calcarious basin out of the
question, we may ask, Was direct creation after the dying out of its
result as a "rugose coral" repeated to constitute the succeeding and
superseding "tabulate coral"? Must we also invoke the miraculous power
to initiate every distinct species of both rugosa and tabulata? These
grand old groups have had their day and are utterly gone. When we
endeavour to conceive or realise such mode of origin, not of them only
but of their manifold successors, the miracle, by the very
multiplication of its manifestations, becomes incredible--inconsistent
with any worthy conception of an all-seeing, all-provident Omnipotence.
Being unable to accept the volitional hypothesis (of Lamarck) or the
selective force exerted by outward circumstances (Darwin), I deem an
innate tendency to deviate from parental type, operating through periods
of adequate duration, to be the most probable way of operation of the
secondary law whereby species have been derived one from another.
According to my derivative hypothesis a change takes place first in the
structure of the animal, and this, when sufficiently advanced, may lead
to modifications of habits. But species owe as little to the accidental
concurrence of environing circumstances as kosmos depends upon a
fortuitous concourse of atoms. A purposive route of development and
change of correlation and inter-dependence, manifesting intelligent
will, is as determinable in the succession of races as in the
development and organisation of the individual.
Derivation holds that every species changes in time, by virtue of
inherent tendencies thereto. Natural selection holds that no such change
can take place without the influence of altered external circumstances
educing or eliciting such change.
Derivation sees among the effects of the innate tendency to change,
irrespective of altered surrounding circumstances, a manifestation of
creative power in the variety and beauty of the results; and, in the
ultimate forthcoming of a being susceptible of appreciating such beauty,
evidence of the preordaining of such relation of power to the
appreciation. Natural selection acknowledges that if power or beauty, in
itself, should be a purpose in creation, it would be absolutely fatal to
it as a hypothesis.
Natural selection sees grandeur in the "view of life, with its several
powers, having been originally breathed by the Creator into a few forms
or into one." Derivation sees, therein, a narrow invocation of a special
miracle and an unworthy limitation of creative power, the grandeur of
which is manifested daily, hourly, in calling into life many forms, by
conversion of physical and chemical into vital modes of force, under as
many diversified conditions of the requisite elements to be so combined.
Natural selection leaves the subsequent origin and succession of species
to the fortuitous concurrence of outward conditions; derivation
recognises a purpose in the defined and preordained course, due to
innate capacity or power of change, by which homogeneously-created
protozoa have risen to the higher forms of plants and animals.
The hypothesis of derivation rests upon conclusions from four great
series of inductively established facts, together with a probable result
of facts of a fifth class; the hypothesis of natural selection totters
on the extension of a conjectural condition explanatory of extinction to
the origination of species, inapplicable in that extension to the
majority of organisms, and not known or observed to apply to the origin
of any species.
_IV.--Epigenesis or Evolution?_
The derivative origin of species, then, being at present the most
admissible one, and the retrospective survey of such species showing
convergence, as time recedes, to more simplified or generalised
organisations, the result to which the suggested train of thought
inevitably leads is very analogous in each instance. If to kosmos or the
mundane system have been allotted powers equivalent to the development
of the several grades of life, may not the demonstrated series of
conversions of force have also included that into the vital form?
In the last century, physiologists were divided as to the principle
guiding the work of organic development.
The "evolutionists" contended that the new being preexisted in a
complete state of formation, needing only to be vivified by impregnation
in order to commence the series of expansions or disencasings,
culminating in the independent individual.
The "epigenesists" held that both the germ and its subsequent organs
were built up of juxtaposed molecules according to the operation of a
developmental force, or "nisus formations."
At the present day the question may seem hardly worth the paper on which
it is referred to. Nevertheless, "pre-existence of germs" and evolution
are logically inseparable from the idea of species by primary
miraculously-created individuals. Cuvier, therefore, maintained both as
firmly as did Haller. In the debates of 1830 I remained the thrall of
that dogma in regard to the origin of single-celled organisms whether in
or out of body. Every result of formfaction, I believed, with most
physiologists, to be the genetic outcome of a pre-existing "cell." The
first was due to miraculous interposition and suspension of ordinary
laws; it contained potentially all future possible cells.
Cell-development exemplified evolution of pre-existing germs, the
progeny of the primary cell. They progagated themselves by
self-division, or by "proliferation" of minutes granules or atoms,
which, when properly nourished, again multiplied by self-division, and
grew to the likeness of the parent cells.
It seems to me more consistent with the present phase of dynamical
science and the observed graduations of living things to suppose the
sarcode or the "protogenal" jelly-speck should be formable through the
concurrence of conditions favouring such combination of their elements,
and involving a change of force productive of their contractions and
extensions, molecular attractions, and repulsions--and the sarcode has
so become, from the period when its irrelative repetitions resulted in
the vast indefinite masses of the "eozoon," exemplifying the earliest
process of "formification" or organic crystallisation--than that all
existing sarcodes or "protogenes" are the result of genetic descent from
a germ or cell due to a primary act of miraculous interposition.
I prefer, while indulging in such speculations, to consider the various
daily nomogeneously developed forms of protozoal or protistal jellies,
sarcodes, and single-celled organisms, to have been as many roots from
which the higher grades have ramified than that the origin of the whole
organic creation is to be referred, as the Egyptian priests did that of
the universe, to a single egg.
Amber or steel, when magnetised, seem to exercise "selection"; they do
not attract all substances alike. A speck of protogenal jelly or
sarcode, if alive, shows analogous relations to certain substances; but
the soft yielding tissue allows the part next the attractive matter to
move thereto, and then, by retraction, to draw such matter into the
sarcodal mass, which overspreads, dissolves, and assimilates it. The
term "living" in the one case is correlative with the term "magnetic" in
the other. A man perceives ripe fruit; he stretches out his hand,
plucks, masticates, swallows, and digests it.
The question then arises whether the difference between such series of
actions in the man and the attractive and assimilative movement of the
amæba be greater or less than the difference between these acts of the
amæba and the attracting and retaining acts of the magnet.
The question, I think, may be put with some confidence as to the quality
of the ultimate reply whether the amæbal phenomena are so much more
different, or so essentially different, from the magnetic phenomena than
they are from the mammalian phenomena, as to necessitate the invocation
of a special miracle for their manifestation. It is analogically
conceivable that the same cause which has endowed His world with power
convertible into magnetic, electric, thermotic and other forms or modes
of force, has also added the conditions of conversion into the vital
force.
From protozoa or protista to plants and animals the graduation is closer
than from magnetised iron to vitalised sarcode. From reflex acts of the
nervous system animals rise to sentient and volitional ones. And with
the ascent are associated brain-cells progressively increasing in size
and complexity. Thought relates to the "brain" of man as does
electricity to the nervous "battery" of the torpedo; both are forms of
force and the results of action of their respective organs.
Each sensation affects a cerebral fibre, and, in so affecting it, gives
it the faculty of repeating the action, wherein memory consists and
sensation in a dream.
If the hypothesis of an abstract entity produces psychological phenomena
by playing upon the brain as a musician upon his instrument be rejected,
and these phenomena be held to be the result of cerebral actions, an
objection is made that the latter view is "materialistic" and adverse to
the notion of an independent, indivisible, "immaterial," mental
principle or soul.
But in the endeavour to comprehend clearly and explain the functions of
the combination of forces called "brain," the physiologist is hindered
and troubled by the views of the nature of those cerebral forces which
the needs of dogmatic theology have imposed on mankind. How long
physiologists would have entertained the notion of a "life," or "vital
principle," as a distinct entity if freed from this baneful influence
may be questioned; but it can be truly affirmed that physiology has now
established and does accept the truth of that statement of Locke--"the
life, whether of a material or immaterial substance, is not the
substance itself, but an affection of it."
RUDOLF VIRCHOW
Cellular Pathology
Rudolf Virchow, the son of a small farmer and shopkeeper, was born
at Schivelbein, in Pomerania, on October 13, 1821. He graduated in
medicine at Berlin, and was appointed lecturer at the University,
but his political enthusiasm brought him into disfavour. In 1849 he
was removed to Wurzburg, where he was made professor of pathology,
but in 1856 he returned to Berlin as Professor and Director of the
Pathological Institute, and there acquired world-wide fame. His
celebrated work, "Cellular Pathology as based on Histology,"
published in 1856, marks a distinct epoch in the science. Virchow
established what Lord Lister describes as "the true and fertile
doctrine that every morbid structure consists of cells which have
been derived from pre-existing cells as a progeny." Virchow was not
only distinguished as a pathologist, he also gained considerable
fame as an archæologist and anthropologist. During the wars of 1866
and 1870-71, he equipped and drilled hospital corps and ambulance
squads, and superintended hospital trains and the Berlin military
hospital. War over, he directed his attention to sanitation and the
sewage problems of Berlin. Virchow was a voluminous author on a
variety of subjects, perhaps his most well-known works being
"Famine Fever" and "Freedom of Science." He died on September 5,
1902.
_The Cell and the Tissues_
The chief point in the application of Histology to Pathology is to
obtain recognition of the fact that the cell is really the ultimate
morphological element in which there is any manifestation of life.
In certain respects animal cells differ from vegetable cells; but in
essentials they are the same; both consist of matter of a nitrogenous
nature.
When we examine a simple cell, we find we can distinguish morphological
parts. In the first place, we find in the cell a round or oval body
known as the nucleus. Occasionally the nucleus is stallate or angular;
but as a rule, so long as cells have vital power, the nucleus maintains
a nearly constant round or oval shape. The nucleus in its turn, in
completely developed cells, very constantly encloses another structure
within itself--the so-called nucleolus. With regard to the question of
vital form, it cannot be said of the nucleolus that it appears to be an
absolute essential, and in a considerable number of young cells it has
as yet escaped detection. On the other hand, we regularly meet with it
in fully-developed, older forms, and it therefore seems to mark a higher
degree of development in the cell.
According to the view which was put forward in the first instance by
Schleiden, and accepted by Schwann, the connection between the three
co-existent cell-constituents was long thought to be of this nature:
that the nucleolus was the first to show itself in the development of
tissues, by separating out of a formative fluid (blastema,
cyto-blastema), that it quickly attained a certain size, that then fine
granules were precipitated out of the blastema and settled around it,
and that about these there condensed a membrane. In this way a nucleus
was formed about which new matter gradually gathered, and in due time
produced a little membrane. This theory of the formation of the cell is
designated the theory of free cell formation--a theory which has been
now almost entirely abandoned.
It is highly probable that the nucleus plays an extremely important part
within the cell--a part less connected with the function and specific
office of the cell, than with its maintenance and multiplication as a
living part. The specific (animal) function is most distinctly
manifested in muscles, nerves, and gland cells, the peculiar actions of
which--contraction, sensation, and secretion--appear to be connected in
no direct manner with the nuclei. But the permanency of the cell as an
element seems to depend on nucleus, for all cells which lose their
nuclei quickly die, and break up, and disappear.
Every organism, whether vegetable or animal, must be regarded as a
progressive total, made up of a larger or smaller number of similar or
dissimilar cells. Just as a tree constitutes a mass arranged in a
definite manner in which, in every single part, in the leaves as in the
root, in the trunk as in the blossom, cells are discovered to be the
ultimate elements, so it is with the forms of animal life. Every animal
presents itself as a sum of vital unities, every one of which manifests
all the characteristics of life. The characteristics and unity of life
cannot be limited to any one particular spot in an organism (for
instance, to the brain of a man) but are to be found only in the
definite, constantly recurring structure, which every individual element
displays. A so-called individual always represents an arrangement of a
social kind, in which a number of individual existences are mutually
dependent, but in such a way that every element has its own special
action, and even though it derive its stimulus to activity from other
parts, yet alone affects the actual performance of its duties.
Between cells there is a greater or less amount of a homogeneous
substance--the _intercellular substance_. According to Schwann, the
intercellular substance was cyto-blastema destined for the development
of new cells; I believe this is not so, I believe that the intercellular
substance is dependent in a certain definite manner upon the cells, and
that certain parts of it belong to one cell and parts to another.
At various times, fibres, globules, and elementary granules, have been
regarded as histological starting-points. Now, however, we have
established the general principle that no development of any kind begins
_de novo_ and that as spontaneous generation is impossible in the case
of entire organisms, so also it is impossible in the case of individual
parts. No cell can build itself up out of non-cellular material. Where a
cell arises, there a cell must have previously existed (omnis cellula e
cellula), just as an animal can spring only from an animal, and a plant
only from a plant. No developed tissues can be traced back to anything
but a cell.
If we wish to classify tissues, a very simple division offers itself. We
have (a) tissues which consist exclusively of cells, where cell lies
close to cell. (b) Tissues in which the cells are separated by a certain
amount of intercellular substance. (c) Tissues of a high or peculiar
type, such as the nervous and muscular systems and vessels. An example
of the first class is seen in the _epithelial_ tissues. In these, cell
lies close to cell, with nothing between.
The second class is exemplified in the _connective_ tissues--tissues
composed of intercellular substance in which at certain intervals cells
lie embedded.
Muscles, nerves, and vessels form a somewhat heterogeneous group. The
idea suggests itself that we have in all three structures to deal with
real tubes filled with more or less movable contents. This view is,
however, inadequate, since we cannot regard the blood as analogous to
the medullary substance of the nerve, or contractile substance of a
muscular fasciculus.
The elements of muscle have generally been regarded as the most simple.
If we examine an ordinary red muscle, we find it to be composed of a
number of cylindrical fibres, marked with transverse and longitudinal
striæ. If, now, we add acetic acid, we discover also tolerably large
nuclei with nucleoli. Thus we obtain an appearance like an elongated
cell, and there is a tendency to regard the primitive fasciculus as
having sprung from a single cell. To this view I am much inclined.
Pathological tissues arise from normal tissues; and there is no form of
morbid growth which cannot in its elements be traced back to some model
which had previously maintained an independent existence in the economy.
A classification, also, of pathological growths may be made on exactly
the same plan as that which we have suggested in the case of the normal
tissues.
_Nutrition, Blood, and Lymph. Pus_
Nutritive material is carried to the tissues by the blood; but the
material is accepted by the tissues only in accordance with their
requirements for the moment, and is conveyed to the individual districts
in suitable quantities. The muscular elements of the arteries have the
most important influence upon the quantity of the blood distributed, and
their elastic elements ensure an equable stream; but it is chiefly the
simple homogeneous membrane of the capillaries that influences the
permeation of the fluids. Not all the peculiarities, however, in the
interchange of nutritive material are to be attributed to the capillary
wall, for no doubt there are chemical affinities which enable certain
parts specially to attract certain substances from the blood. We know,
for example, that a number of substances are introduced into the body
which have special affinities for the nerve tissues, and that certain
materials are excreted by certain organs. We are therefore compelled to
consider the individual elements as active agents of the attraction. If
the living element be altered by disease, then it loses its power of
specific attraction.
I do not regard the blood as the cause of chronic dyscrasiæ; for I do
not regard the blood as a permanent tissue independently regenerating
and propagating itself, but as a fluid in a state of constant dependence
upon other parts. I consider that every dyscrasia _is dependent upon a
permanent supply of noxious ingredients from certain sources_. As a
continual ingestion of injurious food is capable of vitiating the blood,
in like manner persistent disease in a definite organ is able to furnish
the blood with a continual supply of morbid materials.
The essential point, therefore, is to search for the _local sources_ of
the different dyscrasiæ which cause disorders of the blood, for every
permanent change which takes place in the condition of the circulating
juices must be derived from definite organs or tissues.
The blood contains certain morphological elements. It contains a
substance, _fibrine_, which appears as fibrillac when the blood clots,
and red and colourless blood corpuscles.
The red blood corpuscles contain no nuclei except at certain periods of
the development of the embyro. They are lighter or darker red according
to the oxygen they contain. When treated with concentrated fluids they
shrivel; when treated with diluted fluids they swell. They are rather
coin-shaped, and when a drop of blood is quiet they are usually found
aggregated in rows, like rouleaux of money.
The colourless corpuscles are much less numerous than the red
corpuscles--only one to 300--but they are larger, and contain nuclei.
When blood coagulates the white corpuscles sink more slowly and appear
as a lighter coloured layer on the top of the clot.
Pus cells are very like colourless corpuscles, and the relation between
the two has been much debated. A pus cell can be distinguished from a
colourless blood cell only by its mode of origin. If it have an origin
external to the blood, it must be pus; if it originate in the blood, it
must be considered to be a blood cell.
In the early stages of its development, a white blood corpuscle is seen
to modify by division; but in fully-developed blood such division is
never seen. It is probable that colourless white corpuscles are given to
the adult blood by the lymphatic glands. Every irritation of a part
which is freely connected with lymphatic glands increases the number of
colourless cells in the blood. Any excessive increase from this source I
have designated _leucocytosis_.
In the first months of the embryo the red cell multiplies by division.
In adult life the mode of its multiplication is unknown. They, also, are
probably formed in the lymphatic glands and spleen.
In a disease I have named _leukæmia_, the colourless blood cells
increase in number enormously. In such cases there is always disease of
the spleen, and very often of the lymphatic glands.
These facts can hardly, I think, be interpreted in any other manner than
by supposing that the spleen and lymphatic glands are intimately
concerned in the production of the formed elements of the blood.
By _pyæmia_ is meant pus corpuscles in the blood. But most cases of
so-called pyæmia are really cases in which there is an increase of white
blood corpuscles, and it is doubtful whether such a condition as pus in
the blood does ever occur. In the extremely rare cases, in which pus
breaks through into the veins, purulent ingredients may, without doubt,
be conveyed into the blood, but in such cases the introduction of pus
occurs for the most part but once, and there is no persistent pyæmia.
Even when clots in veins break down and form matter like pus, it will be
found that the matter is not really pus, and contains no pus cells.
_Chlorosis_ is a condition in which there is a diminution of the
cellular elements of the blood, due probably to their deficient
formation in the spleen and lymphatic glands.
_The Vital Processes and Their Relation to Disease. Inflammation_
The study of the histology of the nervous system shows that in all parts
of the body a splitting up into a number of small centres takes place,
and that nowhere does a single central point susceptible of anatomical
demonstration exist from which the operations of the body are directed.
We find in the nervous systems definite little cells which serve as
centres of motion, but we do not find any single ganglion cell in which
alone all movement in the end originates. The most various individual
motor apparatuses are connected with the most various individual motor
ganglion cells. Sensations are certainly collected in definite ganglion
cells. Still, among them, too, we do not find any single ganglion cell
which can be in any way designated the centre of all sensation, but we
again meet with a great number of very minute centres. All the
operations which have their source in the nervous system, and there
certainly are a very great number of them, do not allow us to recognise
a unity anywhere else than in our own consciousness. An anatomical or
physiological unity has at least as yet been nowhere demonstrated.
When we talk of life we mean vital activity. Now, every vital action
supposes an excitation or irritation. The irritability of the part is
the criterion by which we judge whether it be alive or not. Our notion
of the death of a part is based upon nothing more or less than
this--that we can no longer detect any irritability in it. If we now
proceed with our analysis of what is to be included in the notion of
excitability, we at once discover, that the different actions which can
be provoked by the influence of any external agency are essentially of
three kinds. The result of an excitation or irritation may, according to
circumstances, be either a merely functional process, or a more or less
increased nutrition of the part, _or_ a formative process giving rise to
a greater or less number of new elements. These differences manifest
themselves more or less distinctly according as the particular tissues
are more or less capable of responding to the one or other kinds of
excitation. It certainly cannot be denied that the processes may not be
distinctly defined, and that between the nutritive and formative
processes, and also between the functional and nutritive ones there are
transitional stages; still, when they are typically performed, there is
a very marked difference between them, and considerable differences in
the internal changes undergone by the excited parts.
In inflammation all three irritative processes occur side by side.
Indeed, we may frequently see that when the organ itself is made up of
different parts, one part of the tissue undergoes functional or
nutritive, another formative, changes. If we consider what happens in a
muscle we see that a chemical or traumatic stimulus produces a
functional irritation of the primitive fasciculi, with contraction of
the muscle followed by nutritive changes. On the other hand, in the
interstitial connective tissue which binds the individual fasciculi of
the muscle together, real new formations are readily produced, commonly
pus. In this manner the three forms of irritation may be distinguished
in one part.
The formative process is always preceded by nutritive enlargement due to
irritation of the part, and has no connection with irritation of the
nerves. Of course there may be also an irritation of the nerves, but
this, if we do not take function into account, has no causal connection
with the processes going on in the tissue proper, but is merely a
collateral effect of the original disturbance.
Besides these active processes of function, nutrition, and new
formation, there occur passive processes. Passive processes are called
those changes in cells whereby they either lose a portion of their
substance, or are so completely destroyed, that a loss of substance, a
diminution of the sum total of the constituents of the body is produced.
To this class belong fatty degeneration of cells, affection of arteries,
calcification, and ossification of arteries, amyloid degeneration, and
so forth.
It will now be necessary to consider inflammation at more length. The
theory of inflammation has passed through various stages. At first heat
was considered as its essential and dominant feature, then redness,
then exudative swelling; while the speculative neuropathologists
consider pain the _fons et origo_ of the condition.
Personally, I believe that irritation must be taken as the
starting-point in the consideration of inflammation. We cannot conceive
of inflammation without an irritating stimulus, and the first question
is, what conception we are to form of such a stimulus.
An inflammatory stimulus is a stimulus which acts either directly or
through the medium of the blood upon the composition and constitution of
a part in such a way as to enable it to attract to itself a larger
quantity of matter than usual and to transform it according to
circumstances. Every form of inflammation with which we are acquainted
may be explained in this way. It may be assumed that inflammation begins
from the moment that this increased absorption of matters into the
tissue takes place, and the further transformation of these matters
commences.
It must be noticed that hyperæmia is not the essential feature of
inflammation, for inflammation occurs in non-vascular as well as in
vascular parts, and the inflammatory processes are practically the same
in both instances.
Nor is inflammatory exudation the essential feature of inflammation. I
am of the opinion that there is no specific inflammatory exudation at
all, but that the exudation we meet with is composed essentially of the
material which has been generated in the inflamed part itself, through
the change in its condition, and of the transuded fluid derived from the
vessels. If, therefore, a part possess a great number of vessels, and
particularly if they are superficial, it will be able to furnish an
exudation, since the fluid which transudes from the blood conveys the
special product of the tissue along with it to the surface. If this is
not the case, there will be no exudation, but the whole process will be
limited to the occurrence in the real substance of the tissue of the
special changes which have been induced by the inflammatory stimulus.
In this manner, two forms of inflammation can be distinguished, the
_purely parenchymatous inflammation_, where the process runs its course
in the interior of the tissue, without our being able to detect the
presence of any free fluid which has escaped from the blood; and the
secretory (exudative) inflammation, where an increased escape of fluid
takes place from the blood, and conveys the peculiar parenchymatous
matters along with it to the surface of the organs. That there are two
kinds of inflammation is shown by the fact that they occur for the most
part in different organs. Every parenchymatous inflammation tends to
alter the histological and functional character of an organ. Every
inflammation with free exudation generally affords a certain relief to
the parts by conveying away from it a great part of the noxious matters
with which it is clogged.
_New Formations_
I at present entirely reject the blastema doctrine in its original form,
and in its place I put the _doctrine of the continuous development of
tissues out of one another_. My first doubts of the blastema doctrine
date from my researches on tubercle. I found the tubercles never
exhibited a discernible exudation; but always organised elements
unpreceded by amorphous matter. I also found that the discharge from
scrofulous glands and from inflamed lymphatic glands is not an exudation
capable of organisation but merely débris, developed from the ordinary
cells of the glands.
Until, however, the cellular nature of the body had been demonstrated,
it seemed necessary in some instances to postulate a blastema or
exudation to account for certain new formations. But the moment I could
show the universality of cells--the moment I could show that bone
corpuscles were real cells, and that connective tissues contained
cells--from that moment cellular material for the building of new
formations was apparent. In fact, the more observers increased the more
distinctly was it shown that by far the greater number of new formations
arise from the connective tissue. In almost all cases new formations may
be seen to be formed by a process of ordinary cell division from
previously existing cells. In some cases the cells continue to resemble
the parent cells; in other cases they become different. All new
formations built of cells which continue true to the parent type we may
call homologous new formations; while those which depart from the parent
type or undergo degenerative changes we may designate heterologous. In a
narrower sense of the word heterologous new formations are alone
destructive. The homologous ones may accidentally become very injurious,
but still they do not possess what can properly be called a destructive
or malignant character. On the other hand, every kind of heterologous
formation whenever it has not its seat in entirely superficial parts,
has a certain degree of malignity, and even superficial affections,
though entirely confined to the most external layers of epidermis, may
gradually exercise a very detrimental effect. Indeed, suppuration is of
this nature, for suppuration is simply a process of proliferation by
means of which cells are produced which do not acquire that degree of
consolidation or permanent connection with each other which is necessary
for the existence of the body. Pus is not the solvent of cells: but is
itself dissolved tissues. A part becomes soft and liquefies, while
suppurating, but it is not the pus which causes this softening; on the
contrary, it is the pus which is produced as the result of the
proliferation of tissues.
A suppurative change of this nature takes place in all heterologous new
formations. The form of ulceration which is presented by cancer in its
latest stages bears so great a resemblance to suppurative ulceration
that the two things have long since been compared. The difference
between suppuration and suppuration lies in the differing duration of
the life of different cells. A cancer cell is capable of existing longer
than a pus corpuscle, and a cancerous tumour may last for months yet
still contain the whole of its elements intact. We are as yet able in
the case of very few elements to state with absolute certainty the
average length of their life. But among all pathological new formations
with fluid intercellular substance there is not a single one which is
able to preserve its existence for any length of time--not a single one
whose elements can become permanent constituents of the body, or exist
as long as the individual. The tumour as a whole may last; but its
individual elements perish. If we examine a tumour after it has existed
for perhaps a year, we usually find that the elements first formed no
longer exist in the centre; but that in the centre they are
disintegrating, dissolved by fatty changes. If a tumour be seated on a
surface, it often presents in the centre of its most prominent part a
navel-like depression, and the parts under this display a dense cicatrix
which no longer bears the original character of the new formation.
Heterologous new formations must be considered parasitical in their
nature, since every one of their elements will withdraw matters from the
body which might be used for better purposes, and since even its first
development implies the destruction of its parent structures.
In view of origin of new formations it were well to create a
nomenclature showing their histological basis; but new names must not be
introduced too suddenly, and it must be noted that there are certain
tumours whose histological pedigree is still uncertain.
_Printed in the United States of America_
FOOTNOTES:
[1] Azure transparent spheres conceived by the ancients to surround the
earth one within another, and to carry the heavenly bodies in their
revolutions.
[2] Book I., Prop. i. The areas which revolving bodies describe by radii
drawn to an immovable centre of force do lie in the same immovable
planes and are proportional to the times in which they are described.
Prop. ii. Every body that moves in any curve line described in a plane
and by a radius drawn to a point either immovable or moving forward with
a uniform rectilinear motion describes about that point areas
proportional to the times is urged by a centripetal force directed to
that point.
Prop. iii. Every body that, by a radius drawn to another body, howsoever
moved, describes areas about that centre proportional to the times is
urged by a force compounded out of the centripetal force tending to that
other body and of all the accelerative force by which that other body is
impelled.
[3] If the periodic times are in the sesquiplicate ratio of the radii,
and therefore the velocities reciprocally in the subduplicate ratio of
the radii, the centripetal forces will be in the duplicate ratio of the
radii inversely; and the converse.
[4] _i.e._, showing convexity when in such a position as that, to an
observer on the earth, a line drawn between it and the sun would subtend
an angle of _90_° or thereabouts.
TRANSCRIBER NOTE:
Variant spelling and punctuation have been preserved.
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