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Title: American Addresses, with a Lecture on the Study of Biology
Author: Tomas Henry Huxley
Release Date: June 26, 2005 [eBook #16136]
Language: English
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AMERICAN ADDRESSES, WITH A LECTURE ON THE STUDY OF BIOLOGY
by
THOMAS H. HUXLEY.
London: MacMillan and Co.
London: R. Clay, Sons, and Taylor, Printers, Bread Street Hill,
Queen Victoria Street.
1877
"Naturæ leges et regulæ, secundum quas omnia fiunt et ex unis
formis in alias mutantur, sunt ubique et semper eadem."
B. DE SPINOZA, _Ethices_, Pars tertia, Præfatio.
CONTENTS.
I. THREE LECTURES ON EVOLUTION (New York, September 18, 20, 22, 1876).
LECTURE I. THE THREE HYPOTHESES RESPECTING THE HISTORY OF NATURE
LECTURE II. THE HYPOTHESIS OF EVOLUTION. THE NEUTRAL AND THE
FAVOURABLE EVIDENCE
LECTURE III. THE DEMONSTRATIVE EVIDENCE OF EVOLUTION
II. AN ADDRESS ON THE OCCASION OF THE OPENING OF THE JOHNS HOPKINS
UNIVERSITY (Baltimore, September 12, 1876)
III. A LECTURE ON THE STUDY OF BIOLOGY, IN CONNECTION WITH THE LOAN
COLLECTION OF SCIENTIFIC APPARATUS (South Kensington Museum,
December 16, 1876)
NEW YORK.
LECTURES ON EVOLUTION.
LECTURE I.
THE THREE HYPOTHESES RESPECTING THE HISTORY OF NATURE.
We live in and form part of a system of things of immense diversity and
perplexity, which we call Nature; and it is a matter of the deepest
interest to all of us that we should form just conceptions of the
constitution of that system and of its past history. With relation to
this universe, man is, in extent, little more than a mathematical point;
in duration but a fleeting shadow; he is a mere reed shaken in the winds
of force. But, as Pascal long ago remarked, although a mere reed, he is
a thinking reed; and in virtue of that wonderful capacity of thought, he
has the power of framing for himself a symbolic conception of the
universe, which, although doubtless highly imperfect and inadequate as a
picture of the great whole, is yet sufficient to serve him as a chart
for the guidance of his practical affairs. It has taken long ages of
toilsome and often fruitless labour to enable man to look steadily at
the shifting scenes of the phantasmagoria of Nature, to notice what is
fixed among her fluctuations, and what is regular among her apparent
irregularities; and it is only comparatively lately, within the last few
centuries, that the conception of a universal order and of a definite
course of things, which we term the course of Nature, has emerged.
But, once originated, the conception of the constancy of the order of
Nature has become the dominant idea of modern thought. To any person who
is familiar with the facts upon which that conception is based, and is
competent to estimate their significance, it has ceased to be
conceivable that chance should have any place in the universe, or that
events should depend upon any but the natural sequence of cause and
effect. We have come to look upon the present as the child of the past
and as the parent of the future; and, as we have excluded chance from a
place in the universe, so we ignore, even as a possibility, the notion
of any interference with the order of Nature. Whatever may be men's
speculative doctrines, it is quite certain, that every intelligent
person guides his life and risks his fortune upon the belief that the
order of Nature is constant, and that the chain of natural causation is
never broken.
In fact, no belief which we entertain has so complete a logical basis as
that to which I have just referred. It tacitly underlies every process
of reasoning; it is the foundation of every act of the will. It is based
upon the broadest induction, and it is verified by the most constant,
regular, and universal of deductive processes. But we must recollect
that any human belief, however broad its basis, however defensible it
may seem, is, after all, only a probable belief, and that our widest and
safest generalizations are simply statements of the highest degree of
probability. Though we are quite clear about the constancy of the order
of Nature, at the present time, and in the present state of things, it
by no means necessarily follows that we are justified in expanding this
generalisation into the infinite past, and in denying, absolutely, that
there may have been a time when Nature did not follow a fixed order,
when the relations of cause and effect were not definite, and when
extra-natural agencies interfered with the general course of Nature.
Cautious men will allow that a universe so different from that which we
know may have existed; just as a very candid thinker may admit that a
world in which two and two do not make four, and in which two straight
lines do inclose a space, may exist. But the same caution which forces
the admission of such possibilities demands a great deal of evidence
before it recognises them to be anything more substantial. And when it
is asserted that, so many thousand years ago, events occurred in a
manner utterly foreign to and inconsistent with the existing laws of
Nature, men, who without being particularly cautious, are simply honest
thinkers, unwilling to deceive themselves or delude others, ask for
trustworthy evidence of the fact.
Did things so happen or did they not? This is a historical question, and
one the answer to which must be sought in the same way as the solution
of any other historical problem.
* * * * *
So far as I know, there are only three hypotheses which ever have been
entertained, or which well can be entertained, respecting the past
history of Nature. I will, in the first place, state the hypotheses, and
then I will consider what evidence bearing upon them is in our
possession, and by what light of criticism that evidence is to be
interpreted.
Upon the first hypothesis, the assumption is, that phenomena of Nature
similar to those exhibited by the present world have always existed; in
other words, that the universe has existed from all eternity in what may
be broadly termed its present condition.
The second hypothesis is, that the present state of things has had only
a limited duration; and that, at some period in the past, a condition of
the world, essentially similar to that which we now know, came into
existence, without any precedent condition from which it could have
naturally proceeded. The assumption that successive states of Nature
have arisen, each without any relation of natural causation to an
antecedent state, is a mere modification of this second hypothesis.
The third hypothesis also assumes that the present state of things has
had but a limited duration; but it supposes that this state has been
evolved by a natural process from an antecedent state, and that from
another, and so on; and, on this hypothesis, the attempt to assign any
limit to the series of past changes is, usually, given up.
It is so needful to form clear and distinct notions of what is really
meant by each of these hypotheses that I will ask you to imagine what,
according to each, would have been visible to a spectator of the events
which constitute the history of the earth. On the first hypothesis,
however far back in time that spectator might be placed, he would see a
world essentially, though perhaps not in all its details, similar to
that which now exists. The animals which existed would be the ancestors
of those which now live, and similar to them; the plants, in like
manner, would be such as we know; and the mountains, plains, and waters
would foreshadow the salient features of our present land and water.
This view was held more or less distinctly, sometimes combined with the
notion of recurrent cycles of change, in ancient times; and its
influence has been felt down to the present day. It is worthy of remark
that it is a hypothesis which is not inconsistent with the doctrine of
Uniformitarianism, with which geologists are familiar. That doctrine was
held by Hutton, and in his earlier days by Lyell. Hutton was struck by
the demonstration of astronomers that the perturbations of the planetary
bodies, however great they may be, yet sooner or later right themselves;
and that the solar system possesses a self-adjusting power by which
these aberrations are all brought back to a mean condition. Hutton
imagined that the like might be true of terrestrial changes; although no
one recognised more clearly than he the fact that the dry land is being
constantly washed down by rain and rivers and deposited in the sea; and
that thus, in a longer or shorter time, the inequalities of the earth's
surface must be levelled, and its high lands brought down to the ocean.
But, taking into account the internal forces of the earth, which,
upheaving the sea-bottom give rise to new land, he thought that these
operations of degradation and elevation might compensate each other; and
that thus, for any assignable time, the general features of our planet
might remain what they are. And inasmuch as, under these circumstances,
there need be no limit to the propagation of animals and plants, it is
clear that the consistent working-out of the uniformitarian idea might
lead to the conception of the eternity of the world. Not that I mean to
say that either Hutton or Lyell held this conception--assuredly not;
they would have been the first to repudiate it. Nevertheless, the
logical development of their arguments tends directly towards this
hypothesis.
The second hypothesis supposes that the present order of things, at some
no very remote time, had a sudden origin, and that the world, such as it
now is, had chaos for its phenomenal antecedent. That is the doctrine
which you will find stated most fully and clearly in the immortal poem
of John Milton--the English _Divina Commedia--Paradise Lost_. I believe
it is largely to the influence of that remarkable work, combined with
the daily teachings to which we have all listened in our childhood, that
this hypothesis owes its general wide diffusion as one of the current
beliefs of English-speaking people. If you turn to the seventh book of
_Paradise Lost_, you will find there stated the hypothesis to which I
refer, which is briefly this: That this visible universe of ours came
into existence at no great distance of time from the present; and that
the parts of which it is composed made their appearance, in a certain
definite order, in the space of six natural days, in such a manner that,
on the first of these days, light appeared; that, on the second, the
firmament, or sky, separated the waters above, from the waters beneath
the firmament; that, on the third day, the waters drew away from the dry
land, and upon it a varied vegetable life, similar to that which now
exists, made its appearance; that the fourth day was signalised by the
apparition of the sun, the stars, the moon, and the planets; that, on
the fifth day, aquatic animals originated within the waters; that, on
the sixth day, the earth gave rise to our four-footed terrestrial
creatures, and to all varieties of terrestrial animals except birds,
which had appeared on the preceding day; and, finally, that man appeared
upon the earth, and the emergence of the universe from chaos was
finished. Milton tells us, without the least ambiguity, what a spectator
of these marvellous occurrences would have witnessed. I doubt not that
his poem is familiar to all of you, but I should like to recall one
passage to your minds, in order that I may be justified in what I have
said regarding the perfectly concrete, definite picture of the origin of
the animal world which Milton draws. He says:--
"The sixth, and of creation last, arose
With evening harps and matin, when God said,
'Let the earth bring forth soul living in her kind,
Cattle and creeping things, and beast of the earth,
Each in their kind!' The earth obeyed, and, straight
Opening her fertile womb, teemed at a birth
Innumerous living creatures, perfect forms,
Limbed and full-grown. Out of the ground uprose,
As from his lair, the wild beast, where he wons
In forest wild, in thicket, brake, or den;
Among the trees in pairs they rose, they walked;
The cattle in the fields and meadows green;
Those rare and solitary; these in flocks
Pasturing at once, and in broad herds upsprung.
The grassy clods now calved; now half appears
The tawny lion, pawing to get free
His hinder parts--then springs, as broke from bonds,
And rampant shakes his brinded mane; the ounce,
The libbard, and the tiger, as the mole
Rising, the crumbled earth above them threw
In hillocks; the swift stag from underground
Bore up his branching head; scarce from his mould
Behemoth, biggest born of earth, upheaved
His vastness; fleeced the flocks and bleating rose
As plants; ambiguous between sea and land,
The river-horse and scaly crocodile.
At once came forth whatever creeps the ground,
Insect or worm."
There is no doubt as to the meaning of this statement, nor as to what a
man of Milton's genius expected would have been actually visible to an
eye-witness of this mode of origination of living things.
The third hypothesis, or the hypothesis of evolution, supposes that, at
any comparatively late period of past time, our imaginary spectator
would meet with a state of things very similar to that which now
obtains; but that the likeness of the past to the present would
gradually become less and less, in proportion to the remoteness of his
period of observation from the present day; that the existing
distribution of mountains and plains, of rivers and seas, would show
itself to be the product of a slow process of natural change operating
upon more and more widely different antecedent conditions of the mineral
framework of the earth; until, at length, in place of that framework, he
would behold only a vast nebulous mass, representing the constituents of
the sun and of the planetary bodies. Preceding the forms of life which
now exist, our observer would see animals and plants not identical with
them, but like them; increasing their differences with their antiquity
and, at the same time, becoming simpler and simpler; until, finally, the
world of life would present nothing but that undifferentiated
protoplasmic matter which, so far as our present knowledge goes, is the
common foundation of all vital activity.
The hypothesis of evolution supposes that in all this vast progression
there would be no breach of continuity, no point at which we could say
"This a natural process," and "This is not a natural process;" but that
the whole might be compared to that wonderful process of development
which may be seen going on every day under our eyes, in virtue of which
there arises, out of the semi-fluid, comparatively homogeneous substance
which we call an egg, the complicated organization of one of the higher
animals. That, in a few words, is what is meant by the hypothesis of
evolution.
* * * * *
I have already suggested that in dealing with these three hypotheses, in
endeavouring to form a judgment as to which of them is the more worthy
of belief, or whether none is worthy of belief--in which case our
condition of mind should be that suspension of judgment which is so
difficult to all but trained intellects--we should be indifferent to all
_à priori_ considerations. The question is a question of historical
fact. The universe has come into existence somehow or other, and the
problem is, whether it came into existence in one fashion, or whether it
came into existence in another; and, as an essential preliminary to
further discussion, permit me to say two or three words as to the nature
and the kinds of historical evidence.
The evidence as to the occurrence of any event in past time may be
ranged under two heads which, for convenience' sake, I will speak of as
testimonial evidence and as circumstantial evidence. By testimonial
evidence I mean human testimony; and by circumstantial evidence I mean
evidence which is not human testimony. Let me illustrate by a familiar
example what I understand by these two kinds of evidence, and what is to
be said respecting their value.
Suppose that a man tells you that he saw a person strike another and
kill him; that is testimonial evidence of the fact of murder. But it is
possible to have circumstantial evidence of the fact of murder; that is
to say, you may find a man dying with a wound upon his head having
exactly the form and character of the wound which is made by an axe,
and, with due care in taking surrounding circumstances into account, you
may conclude with the utmost certainty that the man has been murdered;
that his death is the consequence of a blow inflicted by another man
with that implement. We are very much in the habit of considering
circumstantial evidence as of less value than testimonial evidence, and
it may be that, where the circumstances are not perfectly clear and
intelligible, it is a dangerous and unsafe kind of evidence; but it must
not be forgotten that, in many cases, circumstantial is quite as
conclusive as testimonial evidence, and that, not unfrequently, it is a
great deal weightier than testimonial evidence. For example, take the
case to which I referred just now. The circumstantial evidence may be
better and more convincing than the testimonial evidence; for it may be
impossible, under the conditions that I have defined, to suppose that
the man met his death from any cause but the violent blow of an axe
wielded by another man. The circumstantial evidence in favour of a
murder having been committed, in that case, is as complete and as
convincing as evidence can be. It is evidence which is open to no doubt
and to no falsification. But the testimony of a witness is open to
multitudinous doubts. He may have been mistaken. He may have been
actuated by malice. It has constantly happened that even an accurate man
has declared that a thing has happened in this, that, or the other way,
when a careful analysis of the circumstantial evidence has shown that it
did not happen in that way, but in some other way.
We may now consider the evidence in favour of or against the three
hypotheses. Let me first direct your attention to what is to be said
about the hypothesis of the eternity of the state of things in which we
now live. What will first strike you is, that it is a hypothesis which,
whether true or false, is not capable of verification by any evidence.
For, in order to obtain either circumstantial or testimonial evidence
sufficient to prove the eternity of duration of the present state of
nature, you must have an eternity of witnesses or an infinity of
circumstances, and neither of these is attainable. It is utterly
impossible that such evidence should be carried beyond a certain point
of time; and all that could be said, at most, would be, that so far as
the evidence could be traced, there was nothing to contradict the
hypothesis. But when you look, not to the testimonial evidence--which,
considering the relative insignificance of the antiquity of human
records, might not be good for much in this case--but to the
circumstantial evidence, then you find that this hypothesis is
absolutely incompatible with such evidence as we have; which is of so
plain and so simple a character that it is impossible in any way to
escape from the conclusions which it forces upon us.
You are, doubtless, all aware that the outer substance of the earth,
which alone is accessible to direct observation, is not of a homogeneous
character, but that it is made up of a number of layers or strata, the
titles of the principal groups of which are placed upon the accompanying
diagram. Each of these groups represents a number of beds of sand, of
stone, of clay, of slate, and of various other materials.
[Illustration: FIG. 1.--IDEAL SECTION OF THE CRUST OF THE EARTH.]
On careful examination, it is found that the materials of which each of
these layers of more or less hard rock are composed are, for the most
part, of the same nature as those which are at present being formed
under known conditions on the surface of the earth. For example, the
chalk, which constitutes a great part of the Cretaceous formation in
some parts of the world, is practically identical in its physical and
chemical characters with a substance which is now being formed at the
bottom of the Atlantic Ocean, and covers an enormous area; other beds of
rock are comparable with the sands which are being formed upon
sea-shores, packed together, and so on. Thus, omitting rocks of igneous
origin, it is demonstrable that all these beds of stone, of which a
total of not less than seventy thousand feet is known, have been formed
by natural agencies, either out of the waste and washing of the dry
land, or else by the accumulation of the exuviæ of plants and animals.
Many of these strata are full of such exuviæ--the so-called "fossils."
Remains of thousands of species of animals and plants, as perfectly
recognisable as those of existing forms of life which you meet with in
museums, or as the shells which you pick up upon the sea-beech, have
been imbedded in the ancient sands, or muds, or limestones, just as they
are being imbedded now, in sandy, or clayey, or calcareous subaqueous
deposits. They furnish us with a record, the general nature of which
cannot be misinterpreted, of the kinds of things that have lived upon
the surface of the earth during the time that is registered by this
great thickness of stratified rocks. But even a superficial study of
these fossils shows us that the animals and plants which live at the
present time have had only a temporary duration; for the remains of such
modern forms of life are met with, for the most part, only in the
uppermost or latest tertiaries, and their number rapidly diminishes in
the lower deposits of that epoch. In the older tertiaries, the places of
existing animals and plants are taken by other forms, as numerous and
diversified as those which live now in the same localities, but more or
less different from them; in the mesozoic rocks, these are replaced by
others yet more divergent from modern types; and in the palæozoic
formations the contrast is still more marked. Thus the circumstantial
evidence absolutely negatives the conception of the eternity of the
present condition of things. We can say with certainty that the present
condition of things has existed for a comparatively short period; and
that, so far as animal and vegetable nature are concerned, it has been
preceded by a different condition. We can pursue this evidence until we
reach the lowest of the stratified rocks, in which we lose the
indications of life altogether. The hypothesis of the eternity of the
present state of nature may therefore be put out of court.
We now come to what I will term Milton's hypothesis--the hypothesis that
the present condition of things has endured for a comparatively short
time; and, at the commencement of that time, came into existence within
the course of six days. I doubt not that it may have excited some
surprise in your minds that I should have spoken of this as Milton's
hypothesis, rather than that I should have chosen the terms which are
more customary, such as "the doctrine of creation," or "the Biblical
doctrine," or "the doctrine of Moses," all of which denominations, as
applied to the hypothesis to which I have just referred, are certainly
much more familiar to you than the title of the Miltonic hypothesis. But
I have had what I cannot but think are very weighty reasons for taking
the course which I have pursued. In the first place, I have discarded
the title of the "doctrine of creation," because my present business is
not with the question why the objects which constitute Nature came into
existence, but when they came into existence, and in what order. This is
as strictly a historical question as the question when the Angles and
the Jutes invaded England, and whether they preceded or followed the
Romans. But the question about creation is a philosophical problem, and
one which cannot be solved, or even approached, by the historical
method. What we want to learn is, whether the facts, so far as they are
known, afford evidence that things arose in the way described by Milton,
or whether they do not; and, when that question is settled, it will be
time enough to inquire into the causes of their origination.
In the second place, I have not spoken of this doctrine as the Biblical
doctrine. It is quite true that persons as diverse in their general
views as Milton the Protestant and the celebrated Jesuit Father Suarez,
each put upon the first chapter of Genesis the interpretation embodied
in Milton's poem. It is quite true that this interpretation is that
which has been instilled into every one of us in our childhood; but I do
not for one moment venture to say that it can properly be called the
Biblical doctrine. It is not my business, and does not lie within my
competency, to say what the Hebrew text does, and what it does not
signify; moreover, were I to affirm that this is the Biblical doctrine,
I should be met by the authority of many eminent scholars, to say
nothing of men of science, who, at various times, have absolutely denied
that any such doctrine is to be found in Genesis. If we are to listen to
many expositors of no mean authority, we must believe that what seems so
clearly defined in Genesis--as if very great pains had been taken that
there should be no possibility of mistake--is not the meaning of the
text at all. The account is divided into periods that we may make just
as long or as short as convenience requires. We are also to understand
that it is consistent with the original text to believe that the most
complex plants and animals may have been evolved by natural processes,
lasting for millions of years, out of structureless rudiments. A person
who is not a Hebrew scholar can only stand aside and admire the
marvellous flexibility of a language which admits of such diverse
interpretations. But assuredly, in the face of such contradictions of
authority upon matters respecting which he is incompetent to form any
judgment, he will abstain, as I do, from giving any opinion.
In the third place, I have carefully abstained from speaking of this as
the Mosaic doctrine, because we are now assured upon the authority of
the highest critics, and even of dignitaries of the Church, that there
is no evidence that Moses wrote the Book of Genesis, or knew anything
about it. You will understand that I give no judgment--it would be an
impertinence upon my part to volunteer even a suggestion--upon such a
subject. But, that being the state of opinion among the scholars and the
clergy, it is well for the unlearned in Hebrew lore, and for the laity,
to avoid entangling themselves in such a vexed question. Happily, Milton
leaves us no excuse for doubting what he means, and I shall therefore be
safe in speaking of the opinion in question as the Miltonic hypothesis.
Now we have to test that hypothesis. For my part, I have no prejudice
one way or the other. If there is evidence in favour of this view, I am
burdened by no theoretical difficulties in the way of accepting it; but
there must be evidence. Scientific men get an awkward habit--no, I won't
call it that, for it is a valuable habit--of believing nothing unless
there is evidence for it; and they have a way of looking upon belief
which is not based upon evidence, not only as illogical, but as immoral.
We will, if you please, test this view by the circumstantial evidence
alone; for, from what I have said, you will understand that I do not
propose to discuss the question of what testimonial evidence is to be
adduced in favour of it. If those whose business it is to judge are not
at one as to the authenticity of the only evidence of that kind which is
offered, nor as to the facts to which it bears witness, the discussion
of such evidence is superfluous.
But I may be permitted to regret this necessity of rejecting the
testimonial evidence the less, because the examination of the
circumstantial evidence leads to the conclusion, not only that it is
incompetent to justify the hypothesis, but that, so far as it goes, it
is contrary to the hypothesis.
The considerations upon which I base this conclusion are of the simplest
possible character. The Miltonic hypothesis contains assertions of a
very definite character relating to the succession of living forms. It
is stated that plants, for example, made their appearance upon the third
day, and not before. And you will understand that what the poet means by
plants are such plants as now live, the ancestors, in the ordinary way
of propagation of like by like, of the trees and shrubs which flourish
in the present world. It must needs be so; for, if they were different,
either the existing plants have been the result of a separate
origination since that described by Milton, of which we have no record,
nor any ground for supposition that such an occurrence has taken place;
or else they have arisen by a process of evolution from the original
stocks.
In the second place, it is clear that there was no animal life before
the fifth day, and that, on the fifth day, aquatic animals and birds
appeared. And it is further clear that terrestrial living things, other
than birds, made their appearance upon the sixth day, and not before.
Hence, it follows that, if, in the large mass of circumstantial evidence
as to what really has happened in the past history of the globe we find
indications of the existence of terrestrial animals, other than birds,
at a certain period, it is perfectly certain that all that has taken
place since that time must be referred to the sixth day.
In the great Carboniferous formation, whence America derives so vast a
proportion of her actual and potential wealth, in the beds of coal which
have been formed from the vegetation of that period, we find abundant
evidence of the existence of terrestrial animals. They have been
described, not only by European but by your own naturalists. There are
to be found numerous insects allied to our cockroaches. There are to be
found spiders and scorpions of large size, the latter so similar to
existing scorpions that it requires the practised eye of the naturalist
to distinguish them. Inasmuch as these animals can be proved to have
been alive in the Carboniferous epoch, it is perfectly clear that, if
the Miltonic account is to be accepted, the huge mass of rocks extending
from the middle of the Palæozoic formations to the uppermost members of
the series, must belong to the day which is termed by Milton the sixth.
But, further, it is expressly stated that aquatic animals took their
origin upon the fifth day, and not before; hence, all formations in
which remains of aquatic animals can be proved to exist, and which
therefore testify that such animals lived at the time when these
formations were in course of deposition, must have been deposited during
or since the period which Milton speaks of as the fifth day. But there
is absolutely no fossiliferous formation in which the remains of aquatic
animals are absent. The oldest fossils in the Silurian rocks are exuviæ
of marine animals; and if the view which is entertained by Principal
Dawson and Dr. Carpenter respecting the nature of the _Eozoön_ be well
founded, aquatic animals existed at a period as far antecedent to the
deposition of the coal as the coal is from us; inasmuch as the _Eozoön_
is met with in those Laurentian strata which lie at the bottom of the
series of stratified rocks. Hence it follows, plainly enough, that the
whole series of stratified rocks, if they are to be brought into harmony
with Milton, must be referred to the fifth and sixth days, and that we
cannot hope to find the slightest trace of the products of the earlier
days in the geological record. When we consider these simple facts, we
see how absolutely futile are the attempts that have been made to draw a
parallel between the story told by so much of the crust of the earth as
is known to us and the story which Milton tells. The whole series of
fossiliferous stratified rocks must be referred to the last two days;
and neither the Carboniferous, nor any other, formation can afford
evidence of the work of the third day.
Not only is there this objection to any attempt to establish a harmony
between the Miltonic account and the facts recorded in the fossiliferous
rocks, but there is a further difficulty. According to the Miltonic
account, the order in which animals should have made their appearance in
the stratified rocks would be this: Fishes, including the great whales,
and birds; after them, all varieties of terrestrial animals except
birds. Nothing could be further from the facts as we find them; we know
of not the slightest evidence of the existence of birds before the
Jurassic, or perhaps the Triassic, formation; while terrestrial animals,
as we have just seen, occur in the Carboniferous rocks.
If there were any harmony between the Miltonic account and the
circumstantial evidence, we ought to have abundant evidence of the
existence of birds in the Carboniferous, the Devonian, and the Silurian
rocks. I need hardly say that this is not the case, and that not a trace
of birds makes its appearance until the far later period which I have
mentioned.
And again, if it be true that all varieties of fishes and the great
whales, and the like, made their appearance on the fifth day, we ought
to find the remains of these animals in the older rocks--in those which
were deposited before the Carboniferous epoch. Fishes we do find, in
considerable number and variety; but the great whales are absent, and
the fishes are not such as now live. Not one solitary species of fish
now in existence is to be found in the Devonian or Silurian formations.
Hence we are introduced afresh to the dilemma which I have already
placed before you: either the animals which came into existence on the
fifth day were not such as those which are found at present, are not the
direct and immediate ancestors of those which now exist; in which case
either fresh creations of which nothing is said; or a process of
evolution must have occurred; or else the whole story must be given up,
as not only devoid of any circumstantial evidence, but contrary to such
evidence as exists.
I placed before you in a few words, some little time ago, a statement of
the sum and substance of Milton's hypothesis. Let me now try to state as
briefly, the effect of the circumstantial evidence bearing upon the past
history of the earth which is furnished, without the possibility of
mistake, with no chance of error as to its chief features, by the
stratified rocks. What we find is, that the great series of formations
represents a period of time of which our human chronologies hardly
afford us a unit of measure. I will not pretend to say how we ought to
estimate this time, in millions or in billions of years. For my purpose,
the determination of its absolute duration is wholly unessential. But
that the time was enormous there can be no question.
It results from the simplest methods of interpretation, that leaving out
of view certain patches of metamorphosed rocks, and certain volcanic
products, all that is now dry land has once been at the bottom of the
waters. It is perfectly certain that, at a comparatively recent period
of the world's history--the Cretaceous epoch--none of the great physical
features which at present mark the surface of the globe existed. It is
certain that the Rocky Mountains were not. It is certain that the
Himalaya Mountains were not. It is certain that the Alps and the
Pyrenees had no existence. The evidence is of the plainest possible
character, and is simply this:--We find raised up on the flanks of these
mountains, elevated by the forces of upheaval which have given rise to
them, masses of Cretaceous rock which formed the bottom of the sea
before those mountains existed. It is therefore clear that the elevatory
forces which gave rise to the mountains operated subsequently to the
Cretaceous epoch; and that the mountains themselves are largely made up
of the materials deposited in the sea which once occupied their place.
As we go back in time, we meet with constant alternations of sea and
land, of estuary and open ocean; and, in correspondence with these
alternations, we observe the changes in the fauna and flora to which I
have referred.
But the inspection of these changes give us no right to believe that
there has been any discontinuity in natural processes. There is no trace
of general cataclysms, of universal deluges, or sudden destructions of a
whole fauna or flora. The appearances which were formerly interpreted in
that way have all been shown to be delusive, as our knowledge has
increased and as the blanks which formerly appeared to exist between the
different formations have been filled up. That there is no absolute
break between formation and formation, that there has been no sudden
disappearance of all the forms of life and replacement of them by
others, but that changes have gone on slowly and gradually, that one
type has died out and another has taken its place, and that thus, by
insensible degrees, one fauna has been replaced by another, are
conclusions strengthened by constantly increasing evidence. So that
within the whole of the immense period indicated by the fossiliferous
stratified rocks, there is assuredly not the slightest proof of any
break in the uniformity of Nature's operations, no indication that
events have followed other than a clear and orderly sequence.
That, I say, is the natural and obvious teaching of the circumstantial
evidence contained in the stratified rocks. I leave you to consider how
far, by any ingenuity of interpretation, by any stretching of the
meaning of language, it can be brought into harmony with the Miltonic
hypothesis.
There remains the third hypothesis, that of which I have spoken as the
hypothesis of evolution; and I purpose that, in lectures to come, we
should discuss it as carefully as we have considered the other two
hypotheses. I need not say that it is quite hopeless to look for
testimonial evidence of evolution. The very nature of the case precludes
the possibility of such evidence, for the human race can no more be
expected to testify to its own origin, than a child can be tendered as a
witness of its own birth. Our sole inquiry is, what foundation
circumstantial evidence lends to the hypothesis, or whether it lends
none, or whether it controverts the hypothesis. I shall deal with the
matter entirely as a question of history. I shall not indulge in the
discussion of any speculative probabilities. I shall not attempt to show
that Nature is unintelligible unless we adopt some such hypothesis. For
anything I know about the matter, it may be the way of Nature to be
unintelligible; she is often puzzling, and I have no reason to suppose
that she is bound to fit herself to our notions.
I shall place before you three kinds of evidence entirely based upon
what is known of the forms of animal life which are contained in the
series of stratified rocks. I shall endeavour to show you that there is
one kind of evidence which is neutral, which neither helps evolution nor
is inconsistent with it. I shall then bring forward a second kind of
evidence which indicates a strong probability in favour of evolution,
but does not prove it; and, lastly, I shall adduce a third kind of
evidence which, being as complete as any evidence which we can hope to
obtain upon such a subject, and being wholly and strikingly in favour of
evolution, may fairly be called demonstrative evidence of its
occurrence.
LECTURE II.
THE HYPOTHESIS OF EVOLUTION. THE NEUTRAL AND THE FAVOURABLE EVIDENCE.
In the preceding lecture I pointed out that there are three hypotheses
which may be entertained, and which have been entertained, respecting
the past history of life upon the globe. According to the first of these
hypotheses, living beings, such as now exist, have existed from all
eternity upon this earth. We tested that hypothesis by the
circumstantial evidence, as I called it, which is furnished by the
fossil remains contained in the earth's crust, and we found that it was
obviously untenable. I then proceeded to consider the second hypothesis,
which I termed the Miltonic hypothesis, not because it is of any
particular consequence to me whether John Milton seriously entertained
it or not, but because it is stated in a clear and unmistakable manner
in his great poem. I pointed out to you that the evidence at our command
as completely and fully negatives that hypothesis as it did the
preceding one. And I confess that I had too much respect for your
intelligence to think it necessary to add that the negation was equally
clear and equally valid, whatever the source from which that hypothesis
might be derived, or whatever the authority by which it might be
supported. I further stated that, according to the third hypothesis, or
that of evolution, the existing state of things is the last term of a
long series of states, which, when traced back, would be found to show
no interruption and no breach in the continuity of natural causation. I
propose, in the present, and the following lecture, to test this
hypothesis rigorously by the evidence at command, and to inquire how far
that evidence can be said to be indifferent to it, how far it can be
said to be favourable to it, and, finally, how far it can be said to be
demonstrative.
From almost the origin of the discussions about the existing condition
of the animal and vegetable worlds and the causes which have determined
that condition, an argument has been put forward as an objection to
evolution, which we shall have to consider very seriously. It is an
argument which was first clearly stated by Cuvier in his criticism of
the doctrines propounded by his great contemporary, Lamarck. The French
expedition to Egypt had called the attention of learned men to the
wonderful store of antiquities in that country, and there had been
brought back to France numerous mummified corpses of the animals which
the ancient Egyptians revered and preserved, and which, at a reasonable
computation, must have lived not less than three or four thousand years
before the time at which they were thus brought to light. Cuvier
endeavoured to test the hypothesis that animals have undergone gradual
and progressive modifications of structure, by comparing the skeletons
and such other parts of the mummies as were in a fitting state of
preservation, with the corresponding parts of the representatives of the
same species now living in Egypt. He arrived at the conviction that no
appreciable change had taken place in these animals in the course of
this considerable lapse of time, and the justice of his conclusion is
not disputed.
It is obvious that, if it can be proved that animals have endured,
without undergoing any demonstrable change of structure, for so long a
period as four thousand years, no form of the hypothesis of evolution
which assumes that animals undergo a constant and necessary progressive
change can be tenable; unless, indeed, it be further assumed that four
thousand years is too short a time for the production of a change
sufficiently great to be detected.
But it is no less plain that if the process of evolution of animals is
not independent of surrounding conditions; if it may be indefinitely
hastened or retarded by variations in these conditions; or if evolution
is simply a process of accommodation to varying conditions; the argument
against the hypothesis of evolution based on the unchanged character of
the Egyptian fauna is worthless. For the monuments which are coeval with
the mummies testify as strongly to the absence of change in the physical
geography and the general conditions of the land of Egypt, for the time
in question, as the mummies do to the unvarying characters of its living
population.
The progress of research since Cuvier's time has supplied far more
striking examples of the long duration of specific forms of life than
those which are furnished by the mummified Ibises and Crocodiles of
Egypt. A remarkable case is to be found in your own country, in the
neighbourhood of the falls of Niagara. In the immediate vicinity of the
whirlpool, and again upon Goat Island, in the superficial deposits which
cover the surface of the rocky subsoil in those regions, there are found
remains of animals in perfect preservation, and among them, shells
belonging to exactly the same species as those which at present inhabit
the still waters of Lake Erie. It is evident, from the structure of the
country, that these animal remains were deposited in the beds in which
they occur at a time when the lake extended over the region in which
they are found. This involves the conclusion that they lived and died
before the falls had cut their way back through the gorge of Niagara;
and, indeed, it has been determined that, when these animals lived, the
falls of Niagara must have been at least six miles further down the
river than they are at present. Many computations have been made of the
rate at which the falls are thus cutting their way back. Those
computations have varied greatly, but I believe I am speaking within the
bounds of prudence, if I assume that the falls of Niagara have not
retreated at a greater pace than about a foot a year. Six miles,
speaking roughly, are 30,000 feet; 30,000 feet, at a foot a year, gives
30,000 years; and thus we are fairly justified in concluding that no
less a period than this has passed since the shell-fish, whose remains
are left in the beds to which I have referred, were living creatures.
But there is still stronger evidence of the long duration of certain
types. I have already stated that, as we work our way through the great
series of the Tertiary formations, we find many species of animals
identical with those which live at the present day, diminishing in
numbers, it is true, but still existing, in a certain proportion, in the
oldest of the Tertiary rocks. Furthermore, when we examine the rocks of
the Cretaceous epoch, we find the remains of some animals which the
closest scrutiny cannot show to be, in any important respect, different
from those which live at the present time. That is the case with one of
the cretaceous lamp-shells (_Terebratula_), which has continued to exist
unchanged, or with insignificant variations, down to the present day.
Such is the case with the _Globigerinæ_, the skeletons of which,
aggregated together, form a large proportion of our English chalk. Those
_Globigerinæ_ can be traced down to the _Globigerinæ_ which live at the
surface of the present great oceans, and the remains of which, falling
to the bottom of the sea, give rise to a chalky mud. Hence it must be
admitted that certain existing species of animals show no distinct sign
of modification, or transformation, in the course of a lapse of time as
great as that which carries us back to the Cretaceous period; and which,
whatever its absolute measure, is certainly vastly greater than thirty
thousand years.
There are groups of species so closely allied together that it needs the
eye of a naturalist to distinguish them one from another. If we
disregard the small differences which separate these forms and consider
all the species of such groups as modifications of one type, we shall
find that, even among the higher animals, some types have had a
marvellous duration. In the chalk, for example, there is found a fish
belonging to the highest and the most differentiated group of osseous
fishes, which goes by the name of _Beryx_. The remains of that fish are
among the most beautiful and well preserved of the fossils found in our
English chalk. It can be studied anatomically, so far as the hard parts
are concerned, almost as well as if it were a recent fish. But the genus
_Beryx_ is represented, at the present day, by very closely allied
species which are living in the Pacific and Atlantic Oceans. We may go
still farther back. I have already referred to the fact that the
Carboniferous formations, in Europe and in America, contain the remains
of scorpions in an admirable state of preservation, and that those
scorpions are hardly distinguishable from such as now live. I do not
mean to say that they are not different, but close scrutiny is needed in
order to distinguish them from modern scorpions.
More than this. At the very bottom of the Silurian series, in beds which
are by some authorities referred to the Cambrian formation, where the
signs of life begin to fail us--even there, among the few and scanty
animal remains which are discoverable, we find species of molluscous
animals which are so closely allied to existing forms that, at one time,
they were grouped under the same generic name. I refer to the well-known
_Lingula_ of the _Lingula_ flags, lately, in consequence of some slight
differences, placed in the new genus _Lingulella_. Practically, it
belongs to the same great generic group as the _Lingula_, which is to be
found at the present day upon your own shores and those of many other
parts of the world.
The same truth is exemplified if we turn to certain great periods of the
earth's history--as, for example, the Mesozoic epoch. There are groups
of reptiles, such as the _Ichthyosauria_ and the _Plesiosauria_, which
appear shortly after the commencement of this epoch, and they occur in
vast numbers. They disappear with the chalk and, throughout the whole of
the great series of Mesozoic rocks, they present no such modifications
as can safely be considered evidence of progressive modification.
Facts of this kind are undoubtedly fatal to any form of the doctrine of
evolution which postulates the supposition that there is an intrinsic
necessity, on the part of animal forms which have once come into
existence, to undergo continual modification; and they are as distinctly
opposed to any view which involves the belief, that such modification as
may occur, must take place, at the same rate, in all the different types
of animal or vegetable life. The facts, as I have placed them before
you, obviously directly contradict any form of the hypothesis of
evolution which stands in need of these two postulates.
But, one great service that has been rendered by Mr. Darwin to the
doctrine of evolution in general is this: he has shown that there are
two chief factors in the process of evolution: one of them is the
tendency to vary, the existence of which in all living forms may be
proved by observation; the other is the influence of surrounding
conditions upon what I may call the parent form and the variations which
are thus evolved from it. The cause of the production of variations is a
matter not at all properly understood at present. Whether variation
depends upon some intricate machinery--if I may use the phrase--of the
living organism itself, or whether it arises through the influence of
conditions upon that form, is not certain, and the question may, for the
present, be left open. But the important point is that, granting the
existence of the tendency to the production of variations; then, whether
the variations which are produced shall survive and supplant the parent,
or whether the parent form shall survive and supplant the variations, is
a matter which depends entirely on those conditions which give rise to
the struggle for existence. If the surrounding conditions are such that
the parent form is more competent to deal with them and flourish in
them, than the derived forms, then, in the struggle for existence, the
parent form will maintain itself and the derived forms will be
exterminated. But if, on the contrary, the conditions are such as to be
more favourable to a derived than to the parent form, the parent form
will be extirpated and the derived form will take its place. In the
first case, there will be no progression, no change of structure,
through any imaginable series of ages; in the second place, there will
be modification and change of form.
Thus the existence of these persistent types, as I have termed them, is
no real obstacle in the way of the theory of evolution. Take the case of
the scorpions to which I have just referred. No doubt, since the
Carboniferous epoch, conditions have always obtained, such as existed
when the scorpions of that epoch flourished; conditions in which
scorpions find themselves better off, more competent to deal with the
difficulties in their way, than any variation from the scorpion type
which they may have produced; and, for that reason, the scorpion type
has persisted, and has not been supplanted by any other form. And there
is no reason, in the nature of things, why, as long as this world
exists, if there be conditions more favourable to scorpions than to any
variation which may arise from them, these forms of life should not
persist.
Therefore, the stock objection to the hypothesis of evolution, based on
the long duration of certain animal and vegetable types, is no objection
at all. The facts of this character--and they are numerous--belong to
that class of evidence which I have called indifferent. That is to say,
they may afford no direct support to the doctrine of evolution, but they
are capable of being interpreted in perfect consistency with it.
There is another order of facts belonging to the class of negative or
indifferent evidence. The great group of Lizards, which abound in the
present world, extends through the whole series of formations as far
back as the Permian, or latest Palæozoic, epoch. These Permian lizards
differ astonishingly little from the lizards which exist at the present
day. Comparing the amount of the differences between them and modern
lizards, with the prodigious lapse of time between the Permian epoch and
the present age, it may be said that the amount of change is
insignificant. But, when we carry our researches farther back in time,
we find no trace of lizards, nor of any true reptile whatever, in the
whole mass of formations beneath the Permian.
Now, it is perfectly clear that if our palæontological collections are
to be taken, even approximately, as an adequate representation of all
the forms of animals and plants that have ever lived; and if the record
furnished by the known series of beds of stratified rock, covers the
whole series of events which constitute the history of life on the
globe, such a fact as this directly contravenes the hypothesis of
evolution; because this hypothesis postulates that the existence of
every form must have been preceded by that of some form little different
from it. Here, however, we have to take into consideration that
important truth so well insisted upon by Lyell and by Darwin--the
imperfection of the geological record. It can be demonstrated that the
geological record must be incomplete, that it can only preserve remains
found in certain favourable localities and under particular conditions;
that it must be destroyed by processes of denudation, and obliterated by
processes of metamorphosis. Beds of rock of any thickness, crammed full
of organic remains, may yet, either by the percolation of water through
them, or by the influence of subterranean heat, lose all trace of these
remains, and present the appearance of beds of rock formed under
conditions in which living forms were absent. Such metamorphic rocks
occur in formations of all ages; and, in various cases, there are very
good grounds for the belief that they have contained organic remains,
and that those remains have been absolutely obliterated.
I insist upon the defects of the geological record the more because
those who have not attended to these matters are apt to say, "It is all
very well, but when you get into a difficulty with your theory of
evolution, you appeal to the incompleteness and the imperfection of the
geological record;" and I want to make it perfectly clear to you that
this imperfection is a great fact, which must be taken into account in
all our speculations, or we shall constantly be going wrong.
[Illustration: FIG. 2.--TRACKS OF BRONTOZOUM.]
You see the singular series of footmarks, drawn of its natural size in
the large diagram hanging up here (Fig. 2), which I owe to the kindness
of my friend Professor Marsh, with whom I had the opportunity recently
of visiting the precise locality in Massachusetts in which these tracks
occur. I am, therefore, able to give you my own testimony, if needed,
that the diagram accurately represents what we saw. The valley of the
Connecticut is classical ground for the geologist. It contains great
beds of sandstone, covering many square miles, which have evidently
formed a part of an ancient sea-shore, or, it may be, lake-shore. For a
certain period of time after their deposition, these beds have remained
sufficiently soft to receive the impressions of the feet of whatever
animals walked over them, and to preserve them afterwards, in exactly
the same way as such impressions are at this hour preserved on the
shores of the Bay of Fundy and elsewhere. The diagram represents the
track of some gigantic animal, which walked on its hind legs. You see
the series of marks made alternately by the right and by the left foot;
so that, from one impression to the other of the three-toed foot on the
same side, is one stride, and that stride, as we measured it, is six
feet nine inches. I leave you, therefore, to form an impression of the
magnitude of the creature which, as it walked along the ancient shore,
made these impressions.
Of such impressions there are untold thousands upon these sandstones.
Fifty or sixty different kinds have been discovered, and they cover vast
areas. But, up to this present time, not a bone, not a fragment, of any
one of the animals which left these great footmarks has been found; in
fact, the only animal remains which have been met with in all these
deposits, from the time of their discovery to the present day--though
they have been carefully hunted over--is a fragmentary skeleton of one
of the smaller forms. What has become of the bones of all these animals?
You see we are not dealing with little creatures, but with animals that
make a step of six feet nine inches; and their remains must have been
left somewhere. The probability is, that they been dissolved away, and
absolutely lost.
I have had occasion to work out the nature of fossil remains, of which
there was nothing left except casts of the bones, the solid material of
the skeleton having been dissolved out by percolating water. It was a
chance, in this case, that the sandstone happened to be of such a
constitution as to set, and to allow the bones to be afterward dissolved
out, leaving cavities of the exact shape of the bones. Had that
constitution been other than what it was, the bones would have been
dissolved, the layers of sandstone would have fallen together into one
mass, and not the slightest indication that the animal had existed would
have been discoverable.
I know of no more striking evidence than these facts afford, of the
caution which should be used in drawing the conclusion, from the absence
of organic remains in a deposit, that animals or plants did not exist at
the time it was formed. I believe that, with a right understanding of
the doctrine of evolution on the one hand, and a just estimation of the
importance of the imperfection of the geological record on the other,
all difficulty is removed from the kind of evidence to which I have
adverted; and that we are justified in believing that all such cases are
examples of what I have designated negative or indifferent
evidence--that is to say, they in no way directly advance the hypothesis
of evolution, but they are not to be regarded as obstacles in the way of
our belief in that doctrine.
I now pass on to the consideration of those cases which, for reasons
which I will point out to you by and by, are not to be regarded as
demonstrative of the truth of evolution, but which are such as must
exist if evolution be true, and which therefore are, upon the whole,
evidence in favour of the doctrine. If the doctrine of evolution be
true, it follows, that, however diverse the different groups of animals
and of plants may be, they must all, at one time or other, have been
connected by gradational forms; so that, from the highest animals,
whatever they may be, down to the lowest speck of protoplasmic matter in
which life can be manifested, a series of gradations, leading from one
end of the series to the other, either exists or has existed.
Undoubtedly that is a necessary postulate of the doctrine of evolution.
But when we look upon living Nature as it is, we find a totally
different state of things. We find that animals and plants fall into
groups, the different members of which are pretty closely allied
together, but which are separated by definite, larger or smaller, breaks
from other groups. In other words, no intermediate forms which bridge
over these gaps or intervals are, at present, to be met with.
To illustrate what I mean: Let me call your attention to those
vertebrate animals which are most familiar to you, such as mammals,
birds, and reptiles. At the present day, these groups of animals are
perfectly well defined from one another. We know of no animal now living
which, in any sense, is intermediate between the mammal and the bird, or
between the bird and the reptile; but, on the contrary, there are many
very distinct anatomical peculiarities, well-defined marks, by which the
mammal is separated from the bird, and the bird from the reptile. The
distinctions are obvious and striking if you compare the definitions of
these great groups as they now exist.
The same may be said of many of the subordinate groups, or orders, into
which these great classes are divided. At the present time, for example,
there are numerous forms of non-ruminant pachyderms, or what we may call
broadly, the pig tribe, and many varieties of ruminants. These latter
have their definite characteristics, and the former have their
distinguishing peculiarities. But there is nothing that fills up the gap
between the ruminants and the pig tribe. The two are distinct. Such also
is the case in respect of the minor groups of the class of reptiles. The
existing fauna shows us crocodiles, lizards, snakes, and tortoises; but
no connecting link between the crocodile and lizard, nor between the
lizard and snake, nor between the snake and the crocodile, nor between
any two of these groups. They are separated by absolute breaks. If,
then, it could be shown that this state of things had always existed,
the fact would be fatal to the doctrine of evolution. If the
intermediate gradations, which the doctrine of evolution requires to
have existed between these groups, are not to be found anywhere in the
records of the past history of the globe, their absence is a strong and
weighty negative argument against evolution; while, on the other hand,
if such intermediate forms are to be found, that is so much to the good
of evolution; although, for reasons which I will lay before you by and
by, we must be cautious in our estimate of the evidential cogency of
facts of this kind.
It is a very remarkable circumstance that, from the commencement of the
serious study of fossil remains; in fact, from the time when Cuvier
began his brilliant researches upon those found in the quarries of
Montmartre, palæontology has shown what she was going to do in this
matter, and what kind of evidence it lay in her power to produce.
I said just now that, in the existing Fauna, the group of pig-like
animals and the group of ruminants are entirely distinct; but one of the
first of Cuvier's discoveries was an animal which he called the
_Anoplotherium_, and which proved to be, in a great many important
respects, intermediate in character between the pigs, on the one hand,
and the ruminants on the other. Thus research into the history of the
past did, to a certain extent, tend to fill up the breach between the
group of ruminants and the group of pigs. Another remarkable animal
restored by the great French palæontologist, the _Palæotherium_,
similarly tended to connect together animals to all appearance so
different as the rhinoceros, the horse, and the tapir. Subsequent
research has brought to light multitudes of facts of the same order;
and, at the present day, the investigations of such anatomists as
Rütimeyer and Gaudry have tended to fill up, more and more, the gaps in
our existing series of mammals, and to connect groups formerly thought
to be distinct.
But I think it may have an especial interest if, instead of dealing with
these examples, which would require a great deal of tedious osteological
detail, I take the case of birds and reptiles; groups which, at the
present day, are so clearly distinguished from one another that there
are perhaps no classes of animals which, in popular apprehension, are
more completely separated. Existing birds, as you are aware, are covered
with feathers; their anterior extremities, specially and peculiarly
modified, are converted into wings, by the aid of which most of them are
able to fly; they walk upright upon two legs; and these limbs, when they
are considered anatomically, present a great number of exceedingly
remarkable peculiarities, to which I may have occasion to advert
incidentally as I go on, and which are not met with, even approximately,
in any existing forms of reptiles. On the other hand, existing reptiles
have no feathers. They may have naked skins, or be covered with horny
scales, or bony plates, or with both. They possess no wings; they
neither fly by means of their fore-limbs, nor habitually walk upright
upon their hind-limbs; and the bones of their legs present no such
modifications as we find in birds. It is impossible to imagine any two
groups more definitely and distinctly separated, notwithstanding certain
characters which they possess in common.
As we trace the history of birds back in time, we find their remains,
sometimes in great abundance, throughout the whole extent of the
tertiary rocks; but, so far as our present knowledge goes, the birds of
the tertiary rocks retain the same essential characters as the birds of
the present day. In other words, the tertiary birds come within the
definition of the class constituted by existing birds, and are as much
separated from reptiles as existing birds are. Not very long ago no
remains of birds had been found below the tertiary rocks, and I am not
sure but that some persons were prepared to demonstrate that they could
not have existed at an earlier period. But in the course of the last few
years, such remains have been discovered in England; though,
unfortunately, in so imperfect and fragmentary a condition, that it is
impossible to say whether they differed from existing birds in any
essential character or not. In your country the development of the
cretaceous series of rocks is enormous; the conditions under which the
later cretaceous strata have been deposited are highly favourable to the
preservation of organic remains; and the researches, full of labour and
risk, which have been carried on by Professor Marsh in these cretaceous
rocks of Western America, have rewarded him with the discovery of forms
of birds of which we had hitherto no conception. By his kindness, I am
enabled to place before you a restoration of one of these extraordinary
birds, every part of which can be thoroughly justified by the more or
less complete skeletons, in a very perfect state of preservation, which
he has discovered. This _Hesperornis_ (Fig. 3), which measured between
five and six feet in length, is astonishingly like our existing divers
or grebes in a great many respects; so like them indeed that, had the
skeleton of _Hesperornis_ been found in a museum without its skull, it
probably would have been placed in the same group of birds as the divers
and grebes of the present day.[1]
[Illustration: FIG. 3.--HESPERORNIS REGALIS (Marsh).]
But _Hesperornis_ differs from all existing birds, and so far resembles
reptiles, in one important particular--it is provided with teeth. The
long jaws are armed with teeth which have curved crowns and thick roots
(Fig. 4), and are not set in distinct sockets, but are lodged in a
groove. In possessing true teeth, the _Hesperornis_ differs from every
existing bird, and from every bird yet discovered in the tertiary
formations, the tooth-like serrations of the jaws in the _Odontopteryx_
of the London clay being mere processes of the bony substance of the
jaws, and not teeth in the proper sense of the word. In view of the
characteristics of this bird we are therefore obliged to modify the
definitions of the classes of birds and reptiles. Before the discovery
of _Hesperornis_, the definition of the class Aves based upon our
knowledge of existing birds, might have been extended to all birds; it
might have been said that the absence of teeth was characteristic of the
class of birds; but the discovery of an animal which, in every part of
its skeleton, closely agrees with existing birds, and yet possesses
teeth, shows that there were ancient birds which, in respect of
possessing teeth, approached reptiles more nearly than any existing bird
does, and, to that extent, diminishes the _hiatus_ between the two
classes.
[Illustration: FIG. 4.--HESPERORNIS REGALIS (Marsh).
(Side and upper views of half the lower jaw; side and end views of a
vertebra and a separate tooth.)]
The same formation has yielded another bird _Ichthyornis_ (Fig. 5),
which also possesses teeth; but the teeth are situated in distinct
sockets, while those of _Hesperornis_ are not so lodged. The latter also
has such very small, almost rudimentary, wings, that it must have been
chiefly a swimmer and a diver, like a Penguin; while _Ichthyornis_ has
strong wings and no doubt possessed corresponding powers of flight.
_Ichthyornis_ also differed in the fact that its vertebræ have not the
peculiar characters of the vertebræ of existing and of all known
tertiary birds, but were concave at each end. This discovery leads us to
make a further modification in the definition of the group of birds, and
to part with another of the characters by which almost all existing
birds are distinguished from reptiles.
[Illustration: FIG. 5.--ICHTHYORNIS DISPAR (Marsh).
(Side and upper views of half the lower jaw; and side and end views of a
vertebra.)]
Apart from the few fragmentary remains from the English greensand, to
which I have referred, the mesozoic rocks, older than those in which
_Hesperornis_ and _Ichthyornis_ have been discovered have afforded no
certain evidence of birds, with the remarkable exception of the
Solenhofen slates. These so-called slates are composed of a fine grained
calcareous mud which has hardened into lithographic stone, and in which
organic remains are almost as well preserved as they would be if they
had been imbedded in so much plaster of Paris. They have yielded the
_Archæopteryx_, the existence of which was first made known by the
finding of a fossil feather, or rather of the impression of one. It is
wonderful enough that such a perishable thing as a feather, and nothing
more, should be discovered; yet, for a long time, nothing was known of
this bird except its feather. But, by and by a solitary skeleton was
discovered, which is now in the British Museum. The skull of this
solitary specimen is unfortunately wanting, and it is therefore
uncertain whether the _Archæopteryx_ possessed teeth or not. But the
remainder of the skeleton is so well preserved as to leave no doubt
respecting the main features of the animal, which are very singular. The
feet are not only altogether bird-like, but have the special characters
of the feet of perching birds, while the body had a clothing of true
feathers. Nevertheless, in some other respects, _Archæopteryx_ is unlike
a bird and like a reptile. There is a long tail composed of many
vertebræ. The structure of the wing differs in some very remarkable
respects from that which it presents in a true bird. In the latter, the
end of the wing answers to the thumb and two fingers of my hand; but the
metacarpal bones, or those which answer to the bones of the fingers
which lie in the palm of the hand, are fused together into one mass; and
the whole apparatus, except the last joints of the thumb, is bound up in
a sheath of integument, while the edge of the hand carries the principal
quill-feathers. In the _Archæopteryx_, the upper-arm bone is like that
of a bird; and the two bones of the fore-arm are more or less like those
of a bird, but the fingers are not bound together--they are free. What
their number may have been is uncertain; but several, if not all, of
them were terminated by strong curved claws, not like such as are
sometimes found in birds, but such as reptiles possess; so that, in the
_Archæopteryx_, we have an animal which, to a certain extent, occupies a
midway place between a bird and a reptile. It is a bird so far as its
foot and sundry other parts of its skeleton are concerned; it is
essentially and thoroughly a bird by its feathers; but it is much more
properly a reptile in the fact that the region which represents the hand
has separate bones, with claws resembling those which terminate the
fore-limb of a reptile. Moreover, it had a long reptile-like tail with a
fringe of feathers on each side; while, in all true birds hitherto
known, the tail is relatively short, and the vertebræ which constitute
its skeleton are generally peculiarly modified.
Like the _Anoplotherium_ and the _Palæotherium_, therefore,
_Archæopteryx_ tends to fill up the interval between groups which, in
the existing world, are widely separated, and to destroy the value of
the definitions of zoological groups based upon our knowledge of
existing forms. And such cases as these constitute evidence in favour of
evolution, in so far as they prove that, in former periods of the
world's history, there were animals which overstepped the bounds of
existing groups, and tended to merge them into larger assemblages. They
show that animal organisation is more flexible than our knowledge of
recent forms might have led us to believe; and that many structural
permutations and combinations, of which the present world gives us no
indication, may nevertheless have existed.
But it by no means follows, because the _Palæotherium_ has much in
common with the Horse, on the one hand, and with the Rhinoceros on the
other, that it is the intermediate form through which Rhinoceroses have
passed to become Horses, or _vice versâ_; on the contrary, any such
supposition would certainly be erroneous. Nor do I think it likely that
the transition from the reptile to the bird has been effected by such a
form as _Archæopteryx_. And it is convenient to distinguish these
intermediate forms between two groups, which do not represent the actual
passage from the one group to the other, as _intercalary_ types, from
those _linear_ types which, more or less approximately, indicate the
nature of the steps by which the transition from one group to the other
was effected.
I conceive that such linear forms, constituting a series of natural
gradations between the reptile and the bird, and enabling us to
understand the manner in which the reptilian has been metamorphosed into
the bird type, are really to be found among a group of ancient and
extinct terrestrial reptiles known as the _Ornithoscelida_. The remains
of these animals occur throughout the series of mesozoic formations,
from the Trias to the Chalk, and there are indications of their
existence even in the later Palæozoic strata.
Most of these reptiles at present known are of great size, some having
attained a length of forty feet or perhaps more. The majority resembled
lizards and crocodiles in their general form, and many of them were,
like crocodiles, protected by an armour of heavy bony plates. But, in
others, the hind limbs elongate and the fore limbs shorten, until their
relative proportions approach those which are observed in the
short-winged, flightless, ostrich tribe among birds.
The skull is relatively light, and in some cases the jaws, though
bearing teeth, are beak-like at their extremities and appear to have
been enveloped in a horny sheath. In the part of the vertebral column
which lies between the haunch bones and is called the sacrum, a number
of vertebræ may unite together into one whole, and in this respect, as
in some details of its structure, the sacrum of these reptiles
approaches that of birds.
But it is in the structure of the pelvis and of the hind limb that some
of these ancient reptiles present the most remarkable approximation to
birds, and clearly indicate the way by which the most specialized and
characteristic features of the bird may have been evolved from the
corresponding parts in the reptile.
In Fig. 6, the pelvis and hind limbs of a crocodile, a three-toed bird,
and an ornithoscelidan are represented side by side; and, for facility
of comparison, in corresponding positions; but it must be recollected
that, while the position of the bird's limb is natural, that of the
crocodile is not so. In the bird, the thigh-bone lies close to the body,
and the metatarsal bones of the foot (ii., iii., iv., Fig. 6) are,
ordinarily, raised into a more or less vertical position; in the
crocodile, the thigh-bone stands out at an angle from the body, and the
metatarsal bones (i., ii., iii., iv., Fig. 6) lie flat on the ground.
Hence, in the crocodile, the body usually lies squat between the legs,
while, in the bird, it is raised upon the hind legs, as upon pillars.
In the crocodile, the pelvis is obviously composed of three bones on
each side: the ilium (Il.), the pubis (Pb.), and the ischium (Is.). In
the adult bird there appears to be but one bone on each side. The
examination of the pelvis of a chick, however, shows that each half is
made up of three bones, which answer to those which remain distinct
throughout life, in the crocodile. There is, therefore, a fundamental
identity of plan in the construction of the pelvis of both bird and
reptile; though the differences in form, relative size, and direction of
the corresponding bones in the two cases are very great.
But the most striking contrast between the two lies in the bones of the
leg and of that part of the foot termed the tarsus, which follows upon
the leg. In the crocodile, the fibula (F) is relatively large and its
lower end is complete. The tibia (T) has no marked crest at its upper
end, and its lower end is narrow and not pulley-shaped. There are two
rows of separate tarsal bones (As., Ca., &c.) and four distinct
metatarsal bones, with a rudiment of a fifth.
In the bird, the fibula is small and its lower end diminishes to a
point. The tibia has a strong crest at its upper end and its lower
extremity passes into a broad pulley. There seem at first to be no
tarsal bones; and only one bone, divided at the end into three heads for
the three toes which are attached to it, appears in the place of the
metatarsus.
In a young bird, however, the pulley-shaped apparent end of the tibia is
a distinct bone, which represents the bones marked As., Ca., in the
crocodile; while the apparently single metatarsal bone consists of three
bones, which early unite with one another and with an additional bone,
which represents the lower row of bones in the tarsus of the crocodile.
In other words, it can be shown by the study of development that the
bird's pelvis and hind limb are simply extreme modifications of the same
fundamental plan as that upon which these parts are modelled in
reptiles.
[Illustration: FIG. 6.--BIRD. ORNITHOSCELIDAN. CROCODILE.
(The letters have the same signification in all the figures. Il.,
Ilium; a, anterior end; b, posterior end; Is., ischium; Pb.,
pubis; T, tibia; F, fibula; As., astragalus; Ca., calcaneum; 1,
distal portion of the tarsus; i., ii., iii., iv.; metatarsal bones.)]
On comparing the pelvis and hind limb of the ornithoscelidan with that
of the crocodile, on the one side, and that of the bird, on the other
(Fig. 6), it is obvious that it represents a middle term between the
two. The pelvic bones approach the form of those of the birds, and the
direction of the pubis and ischium is nearly that which is
characteristic of birds; the thigh bone, from the direction of its head,
must have lain close to the body; the tibia has a great crest; and,
immovably fitted on to its lower end, there is a pulley-shaped bone,
like that of the bird, but remaining distinct. The lower end of the
fibula is much more slender, proportionally, than in the crocodile. The
metatarsal bones have such a form that they fit together immovably,
though they do not enter into bony union; the third toe is, as in the
bird, longest and strongest. In fact, the ornithoscelidan limb is
comparable to that of an unhatched chick.
Taking all these facts together, it is obvious that the view, which was
entertained by Mantell and the probability of which was demonstrated by
your own distinguished anatomist, Leidy, while much additional evidence
in the same direction has been furnished by Professor Cope, that some of
these animals may have walked upon their hind legs, as birds do,
acquires great weight. In fact, there can be no reasonable doubt that
one of the smaller forms of the _Ornithoscelida_, _Compsognathus_, the
almost entire skeleton of which has been discovered in the Solenhofen
slates, was a bipedal animal. The parts of this skeleton are somewhat
twisted out of their natural relations, but the accompanying figure
gives a just view of the general form of _Compsognathus_ and of the
proportions of its limbs; which, in some respects, are more completely
bird-like than those of other _Ornithoscelida_.
[Illustration: FIG. 7.--RESTORATION OF COMPSOGNATHUS LONGIPES.]
We have had to stretch the definition of the class of birds so as to
include birds with teeth and birds with paw-like fore-limbs and long
tails. There is no evidence that _Compsognathus_ possessed feathers;
but, if it did, it would be hard indeed to say whether it should be
called a reptilian bird or an avian reptile.
As _Compsognathus_ walked upon its hind legs, it must have made tracks
like those of birds. And as the structure of the limbs of several of the
gigantic _Ornithoscelida_, such as _Iguandon_, leads to the conclusion
that they also may have constantly, or occasionally, assumed the same
attitude, a peculiar interest attaches to the fact that, in the Wealden
strata of England, there are to be found gigantic footsteps, arranged in
order like those of the _Brontozoum_, and which there can be no
reasonable doubt were made by some of the _Ornithoscelida_, the remains
of which are found in the same rocks. And, knowing that reptiles that
walked upon their hind legs and shared many of the anatomical characters
of birds did once exist, it becomes a very important question whether
the tracks in the Trias of Massachusetts, to which I referred some time
ago, and which formerly used to be unhesitatingly ascribed to birds, may
not all have been made by Ornithoscelidan reptiles; and whether, if we
could obtain the skeletons of the animals which made these tracks, we
should not find in them the actual steps of the evolutional process by
which reptiles gave rise to birds.
The evidential value of the facts I have brought forward in this Lecture
must be neither over nor under estimated. It is not historical proof of
the occurrence of the evolution of birds from reptiles, for we have no
safe ground for assuming that true birds had not made their appearance
at the commencement of the Mesozoic epoch. It is, in fact, quite
possible that all these more or less avi-form reptiles of the Mesozoic
epoch are not terms in the series of progression from birds to reptiles
at all but simply the more or less modified descendants of Palæozoic
forms through which that transition was actually effected.
We are not in a position to say that the known _Ornithoscelida_ are
intermediate in the order of their appearance on the earth between
reptiles and birds. All that can be said is that, if independent
evidence of the actual occurrence of evolution is producible, then these
intercalary forms remove every difficulty in the way of understanding
what the actual steps of the process, in the case of birds, may have
been.
That intercalary forms should have existed in ancient times is a
necessary consequence of the truth of the hypothesis of evolution; and,
hence, the evidence I have laid before you in proof of the existence of
such forms, is, so far as it goes, in favour of that hypothesis.
There is another series of extinct reptiles, which may be said to be
intercalary between reptiles and birds, in so far as they combine some
of the characters of both these groups; and, which, as they possessed
the power of flight, may seem, at first sight, to be nearer
representatives of the forms by which the transition from the reptile to
the bird was effected, than the _Ornithoscelida_.
[Illustration: FIG. 8.--PTERODACTYLUS SPECTABILIS (Von Meyer).]
These are the _Pterosauria_, or Pterodactyles, the remains of which are
met with throughout the series of Mesozoic rocks, from the lias to the
chalk, and some of which attained a great size, their wings having a
span of eighteen or twenty feet. These animals, in the form and
proportions of the head and neck relatively to the body, and in the fact
that the ends of the jaws were often, if not always, more or less
extensively ensheathed in horny beaks, remind us of birds. Moreover,
their bones contained air cavities, rendering them specifically lighter,
as is the case in most birds. The breast-bone was large and keeled, as in
most birds and in bats, and the shoulder girdle is strikingly similar to
that of ordinary birds. But, it seems to me, that the special
resemblance of pterodactyles to birds ends here, unless I may add the
entire absence of teeth which characterizes the great pterodactyles
(_Pteranodon_), discovered by Professor Marsh. All other known
pterodactyles have teeth lodged in sockets. In the vertebral column and
the hind limbs there are no special resemblances to birds, and when we
turn to the wings they are found to be constructed on a totally
different principle from those of birds.
There are four fingers. These four fingers are large, and three of them,
those which answer to the thumb and two following fingers in my
hand--are terminated by claws, while the fourth is enormously prolonged
and converted into a great jointed style. You see at once, from what I
have stated about a bird's wing, that there could be nothing less like a
bird's wing than this is. It concluded by general reasoning that this
finger had the office of supporting a web which extended between it and
the body. An existing specimen proves that such was really the case, and
that the pterodactyles were devoid of feathers, but that the fingers
supported a vast web like that of a bat's wing; in fact, there can be no
doubt that this ancient reptile flew after the fashion of a bat.
Thus though the pterodactyle is a reptile which has become modified in
such a manner as to enable it to fly, and therefore, as might be
expected, presents some points of resemblance to other animals which
fly; it has, so to speak, gone off the line which leads directly from
reptiles to birds, and has become disqualified for the changes which
lead to the characteristic organization of the latter class. Therefore,
viewed in relation to the classes of reptiles and birds, the
pterodactyles appear to me to be, in a limited sense, intercalary forms;
but they are not even approximately linear, in the sense of exemplifying
those modifications of structure through which the passage from the
reptile to the bird took place.
LECTURE III.
THE DEMONSTRATIVE EVIDENCE OF EVOLUTION.
The occurrence of historical facts is said to be demonstrated, when the
evidence that they happened is of such a character as to render the
assumption that they did not happen in the highest degree improbable;
and the question I now have to deal with is, whether evidence in favour
of the evolution of animals of this degree of cogency is, or is not,
obtainable from the record of the succession of living forms which is
presented to us by fossil remains.
Those who have attended to the progress of palæontology are aware that
evidence of the character which I have defined has been produced in
considerable and continually-increasing quantity during the last few
years. Indeed, the amount and the satisfactory nature of that evidence
are somewhat surprising, when we consider the conditions under which
alone we can hope to obtain it.
It is obviously useless to seek for such evidence except in localities
in which the physical conditions have been such as to permit of the
deposit of an unbroken, or but rarely interrupted, series of strata
through a long period of time; in which the group of animals to be
investigated has existed in such abundance as to furnish the requisite
supply of remains; and in which, finally, the materials composing the
strata are such as to ensure the preservation of these remains in a
tolerably perfect and undisturbed state.
It so happens that the case which, at present, most nearly fulfils all
these conditions is that of the series of extinct animals which
culminates in the Horses; by which term I mean to denote not merely the
domestic animals with which we are all so well acquainted, but their
allies, the ass, zebra, quagga, and the like. In short, I use "horses"
as the equivalent of the technical name _Equidæ_, which is applied to
the whole group of existing equine animals.
The horse is in many ways a remarkable animal; not least so in the fact
that it presents us with an example of one of the most perfect pieces of
machinery in the living world. In truth, among the works of human
ingenuity it cannot be said that there is any locomotive so perfectly
adapted to its purposes, doing so much work with so small a quantity of
fuel, as this machine of nature's manufacture--the horse. And, as a
necessary consequence of any sort of perfection, of mechanical
perfection as of others, you find that the horse is a beautiful
creature, one of the most beautiful of all land-animals. Look at the
perfect balance of its form, and the rhythm and force of its action. The
locomotive machinery is, as you are aware, resident in its slender fore
and hind limbs; they are flexible and elastic levers, capable of being
moved by very powerful muscles; and, in order to supply the engines
which work these levers with the force which they expend, the horse is
provided with a very perfect apparatus for grinding its food and
extracting therefrom the requisite fuel.
Without attempting to take you very far into the region of osteological
detail, I must nevertheless trouble you with some statements respecting
the anatomical structure of the horse; and, more especially, will it be
needful to obtain a general conception of the structure of its fore and
hind limbs, and of its teeth. But I shall only touch upon those points
which are absolutely essential to our inquiry.
Let us turn in the first place to the fore-limb. In most quadrupeds, as
in ourselves, the fore-arm contains distinct bones called the radius and
the ulna. The corresponding region in the Horse seem at first to possess
but one bone. Careful observation, however, enables us to distinguish in
this bone a part which clearly answers to the upper end of the ulna.
This is closely united with the chief mass of the bone which represents
the radius, and runs out into a slender shaft which may be traced for
some distance downwards upon the back of the radius, and then in most
cases thins out and vanishes. It takes still more trouble to make sure
of what is nevertheless the fact, that a small part of the lower end of
the bone of the horse's fore-arm, which is only distinct in a very young
foal, is really the lower extremity of the ulna.
What is commonly called the knee of a horse is its wrist. The "cannon
bone" answers to the middle bone of the five metacarpal bones, which
support the palm of the hand in ourselves. The "pastern," "coronary,"
and "coffin" bones of veterinarians answer to the joints of our middle
fingers, while the hoof is simply a greatly enlarged and thickened nail.
But if what lies below the horse's "knee" thus corresponds to the middle
finger in ourselves, what has become of the four other fingers or
digits? We find in the places of the second and fourth digits only two
slender splint-like bones, about two-thirds as long as the cannon bone,
which gradually taper to their lower ends and bear no finger joints, or,
as they are termed, phalanges. Sometimes, small bony or gristly nodules
are to be found at the bases of these two metacarpal splints, and it is
probable that these represent rudiments of the first and fifth toes.
Thus, the part of the horse's skeleton, which corresponds with that of
the human hand, contains one overgrown middle digit, and at least two
imperfect lateral digits; and these answer, respectively, to the third,
the second, and the fourth fingers in man.
Corresponding modifications are found in the hind limb. In ourselves,
and in most quadrupeds, the leg contains two distinct bones, a large
bone, the tibia, and a smaller and more slender bone, the fibula. But,
in the horse, the fibula seems, at first, to be reduced to its upper
end; a short slender bone united with the tibia, and ending in a point
below, occupying its place. Examination of the lower end of a young
foal's shin-bone, however, shows a distinct portion of osseous matter,
which is the lower end of the fibula; so that the, apparently single,
lower end of the shin-bone is really made up of the coalesced ends of
the tibia and fibula, just as the, apparently single, lower end of the
fore-arm bone is composed of the coalesced radius and ulna.
The heel of the horse is the part commonly known as the hock. The hinder
cannon bone answers to the middle metatarsal bone of the human foot, the
pastern, coronary, and coffin bones, to the middle toe bones; the hind
hoof to the nail; as in the fore-foot. And, as in the fore-foot, there
are merely two splints to represent the second and the fourth toes.
Sometimes a rudiment of a fifth toe appears to be traceable.
The teeth of a horse are not less peculiar than its limbs. The living
engine, like all others, must be well stoked if it is to do its work;
and the horse, if it is to make good its wear and tear, and to exert the
enormous amount of force required for its propulsion, must be well and
rapidly fed. To this end, good cutting instruments and powerful and
lasting crushers are needful. Accordingly, the twelve cutting teeth of a
horse are close-set and concentrated in the fore part of its mouth, like
so many adzes or chisels. The grinders or molars are large, and have an
extremely complicated structure, being composed of a number of different
substances of unequal hardness. The consequence of this is that they
wear away at different rates; and, hence, the surface of each grinder is
always as uneven as that of a good millstone.
I have said that the structure of the grinding teeth is very
complicated, the harder and the softer parts being, as it were,
interlaced with one another. The result of this is that, as the tooth
wears, the crown presents a peculiar pattern, the nature of which is not
very easily deciphered at first; but which it is important we should
understand clearly. Each grinding tooth of the upper jaw has an _outer
wall_ so shaped that, on the worn crown, it exhibits the form of two
crescents, one in front and one behind, with their concave sides turned
outwards. From the inner side of the front crescent, a crescentic _front
ridge_ passes inwards and backwards, and its inner face enlarges into a
strong longitudinal fold or _pillar_. From the front part of the hinder
crescent, a _back ridge_ takes a like direction, and also has its
_pillar_.
The deep interspaces or _valleys_ between these ridges and the outer
wall are filled by bony substance, which is called _cement_, and coats
the whole tooth.
The pattern of the worn face of each grinding tooth of the lower jaw is
quite different. It appears to be formed of two crescent-shaped ridges,
the convexities of which are turned outwards. The free extremity of each
crescent has a _pillar_, and there is a large double _pillar_ where the
two crescents meet. The whole structure is, as it were, imbedded in
cement, which fills up the valleys, as in the upper grinders.
If the grinding faces of an upper and of a lower molar of the same side
are applied together, it will be seen that the apposed ridges are
nowhere parallel, but that they frequently cross; and that thus, in the
act of mastication, a hard surface in the one is constantly applied to a
soft surface in the other, and _vice versâ_. They thus constitute a
grinding apparatus of great efficiency, and one which is repaired as
fast as it wears, owing to the long-continued growth of the teeth.
Some other peculiarities of the dentition of the horse must be noticed,
as they bear upon what I shall have to say by and by. Thus the crowns of
the cutting teeth have a peculiar deep pit, which gives rise to the
well-known "mark" of the horse. There is a large space between the outer
incisors and the front grinder. In this space the adult male horse
presents, near the incisors on each side, above and below, a canine or
"tush," which is commonly absent in mares. In a young horse, moreover,
there is not unfrequently to be seen in front of the first grinder, a
very small tooth, which soon falls out. If this small tooth be counted
as one, it will be found that there are seven teeth behind the canine on
each side; namely, the small tooth in question, and the six great
grinders, among which, by an unusual peculiarity, the foremost tooth is
rather larger than those which follow it.
I have now enumerated those characteristic structures of the horse which
are of most importance for the purpose we have in view.
To any one who is acquainted with the morphology of vertebrated animals,
they show that the horse deviates widely from the general structure of
mammals; and that the horse type is, in many respects, an extreme
modification of the general mammalian plan. The least modified mammals,
in fact, have the radius and ulna, the tibia and fibula, distinct and
separate. They have five distinct and complete digits on each foot, and
no one of these digits is very much larger than the rest. Moreover, in
the least modified mammals, the total number of the teeth is very
generally forty-four, while in horses, the usual number is forty, and in
the absence of the canines, it may be reduced to thirty-six; the incisor
teeth are devoid of the fold seen in those of the horse: the grinders
regularly diminish in size from the middle of the series to its front
end; while their crowns are short, early attain their full length, and
exhibit simple ridges or tubercles, in place of the complex foldings of
the horse's grinders.
Hence the general principles of the hypothesis of evolution lead to the
conclusion that the horse must have been derived from some quadruped
which possessed five complete digits on each foot; which had the bones
of the fore-arm and of the leg complete and separate; and which
possessed forty-four teeth, among which the crowns of the incisors and
grinders had a simple structure; while the latter gradually increased in
size from before backwards, at any rate in the anterior part of the
series, and had short crowns.
And if the horse has been thus evolved, and the remains of the different
stages of its evolution have been preserved, they ought to present us
with a series of forms in which the number of the digits becomes
reduced; the bones of the fore-arm and leg gradually take on the equine
condition; and the form and arrangement of the teeth successively
approximate to those which obtain in existing horses.
Let us turn to the facts, and see how far they fulfil these requirements
of the doctrine of evolution.
In Europe abundant remains of horses are found in the Quaternary and
later Tertiary strata as far as the Pliocene formation. But these
horses, which are so common in the cave-deposits and in the gravels of
Europe, are in all essential respects like existing horses. And that is
true of all the horses of the latter part of the Pliocene epoch. But, in
deposits which belong to the earlier Pliocene and later Miocene epochs,
and which occur in Britain, in France, in Germany, in Greece, in India,
we find animals which are extremely like horses--which, in fact, are so
similar to horses, that you may follow descriptions given in works upon
the anatomy of the horse upon the skeletons of these animals--but which
differ in some important particulars. For example, the structure of
their fore and hind limbs is somewhat different. The bones which, in the
horse, are represented by two splints, imperfect below, are as long as
the middle metacarpal and metatarsal bones; and, attached to the
extremity of each, is a digit with three joints of the same general
character as those of the middle digit, only very much smaller. These
small digits are so disposed that they could have had but very little
functional importance, and they must have been rather of the nature of
the dew-claws, such as are to be found in many ruminant animals. The
_Hipparion_, as the extinct European three-toed horse is called, in
fact, presents a foot similar to that of the American _Protohippus_
(Fig. 9), except that, in the _Hipparion_, the smaller digits are
situated farther back, and are of smaller proportional size, than in the
_Protohippus_.
The ulna is slightly more distinct than in the horse; and the whole
length of it, as a very slender shaft, intimately united with the
radius, is completely traceable. The fibula appears to be in the same
condition as in the horse. The teeth of the _Hipparion_ are essentially
similar to those of the horse, but the pattern of the grinders is in
some respects a little more complex, and there is a depression on the
face of the skull in front of the orbit, which is not seen in existing
horses.
In the earlier Miocene, and perhaps the later Eocene deposits of some
parts of Europe, another extinct animal has been discovered, which
Cuvier, who first described some fragments of it, considered to be a
_Palæotherium_. But as further discoveries threw new light upon its
structure, it was recognised as a distinct genus, under the name of
_Anchitherium_.
In its general characters, the skeleton of _Anchitherium_ is very
similar to that of the horse. In fact, Lartet and De Blainville called
it _Palæotherium equinum_ or _hippoides_; and De Christol, in 1847, said
that it differed from _Hipparion_ in little more than the characters of
its teeth, and gave it the name of _Hipparitherium_. Each foot possesses
three complete toes; while the lateral toes are much larger in
proportion to the middle toe than in _Hipparion_, and doubtless rested
on the ground in ordinary locomotion.
The ulna is complete and quite distinct from the radius, though firmly
united with the latter. The fibula seems also to have been complete. Its
lower end, though intimately united with that of the tibia, is clearly
marked off from the latter bone.
There are forty-four teeth. The incisors have no strong pit. The canines
seem to have been well developed in both sexes. The first of the seven
grinders, which, as I have said, is frequently absent, and, when it does
exist, is small in the horse, is a good-sized and permanent tooth, while
the grinder which follows it is but little larger than the hinder ones.
The crowns of the grinders are short, and though the fundamental pattern
of the horse-tooth is discernible, the front and back ridges are less
curved, the accessory pillars are wanting, and the valleys, much
shallower, are not filled up with cement.
Seven years ago, when I happened to be looking critically into the
bearing of palæontological facts upon the doctrine of evolution, it
appeared to me that the _Anchitherium_, the _Hipparion_, and the modern
horses, constitute a series in which the modifications of structure
coincide with the order of chronological occurrence, in the manner in
which they must coincide, if the modern horses really are the result of
the gradual metamorphosis, in the course of the Tertiary epoch, of a
less specialised ancestral form. And I found by correspondence with the
late eminent French anatomist and palæontologist, M. Lartet, that he had
arrived at the same conclusion from the same data.
That the _Anchitherium_ type had become metamorphosed into the
_Hipparion_ type, and the latter into the _Equine_ type, in the course
of that period of time which is represented by the latter half of the
Tertiary deposits, seemed to me to be the only explanation of the facts
for which there was even a shadow of probability.[2]
And, hence, I have ever since held that these facts afford evidence of
the occurrence of evolution, which, in the sense already defined, may be
termed demonstrative.
All who have occupied themselves with the structure of _Anchitherium_,
from Cuvier onwards, have acknowledged its many points of likeness to a
well-known genus of extinct Eocene mammals, _Palæotherium_. Indeed, as
we have seen, Cuvier regarded his remains of _Anchitherium_ as those of
a species of _Palæotherium_. Hence, in attempting to trace the pedigree
of the horse beyond the Miocene epoch and the Anchitheroid form, I
naturally sought among the various species of Palæotheroid animals for
its nearest ally, and I was led to conclude that the _Palæotherium
minus (Plagiolophus)_ represented the next step more nearly than any
form then known.
I think that this opinion was fully justifiable; but the progress of
investigation has thrown an unexpected light on the question, and has
brought us much nearer than could have been anticipated to a knowledge
of the true series of the progenitors of the horse.
You are all aware that, when your country was first discovered by
Europeans, there were no traces of the existence of the horse in any
part of the American Continent. The accounts of the conquest of Mexico
dwell upon the astonishment of the natives of that country when they
first became acquainted with that astounding phenomenon--a man seated
upon a horse. Nevertheless, the investigations of American geologists
have proved that the remains of horses occur in the most superficial
deposits of both North and South America, just as they do in Europe.
Therefore, for some reason or other--no feasible suggestion on that
subject, so far as I know, has been made--the horse must have died out
on this continent at some period preceding the discovery of America. Of
late years there has been discovered in your Western Territories that
marvellous accumulation of deposits, admirably adapted for the
preservation of organic remains, to which I referred the other evening,
and which furnishes us with a consecutive series of records of the fauna
of the older half of the Tertiary epoch, for which we have no parallel
in Europe. They have yielded fossils in an excellent state of
conservation and in unexampled number and variety. The researches of
Leidy and others have shown that forms allied to the _Hipparion_ and the
_Anchitherium_ are to be found among these remains. But it is only
recently that the admirably conceived and most thoroughly and patiently
worked-out investigations of Professor Marsh have given us a just idea
of the vast fossil wealth, and of the scientific importance, of these
deposits. I have had the advantage of glancing over the collections in
Yale Museum; and I can truly say that, so far as my knowledge extends,
there is no collection from any one region and series of strata
comparable, for extent, or for the care with which the remains have been
got together, or for their scientific importance, to the series of
fossils which he has deposited there. This vast collection has yielded
evidence bearing upon the question of the pedigree of the horse of the
most striking character. It tends to show that we must look to America,
rather than to Europe, for the original seat of the equine series; and
that the archaic forms and successive modifications of the horse's
ancestry are far better preserved here than in Europe.
Professor Marsh's kindness has enabled me to put before you a diagram,
every figure in which is an actual representation of some specimen which
is to be seen at Yale at this present time (Fig. 9).
[Illustration: FIG. 9.]
The succession of forms which he has brought together carries us from
the top to the bottom of the Tertiaries. Firstly, there is the true
horse. Next we have the American Pliocene form of the horse
(_Pliohippus_); in the conformation of its limbs it presents some very
slight deviations from the ordinary horse, and the crowns of the
grinding teeth are shorter. Then comes the _Protohippus_, which
represents the European _Hipparion_, having one large digit and two
small ones on each foot, and the general characters of the fore-arm and
leg to which I have referred. But it is more valuable than the European
_Hipparion_ for the reason that it is devoid of some of the
peculiarities of that form--peculiarities which tend to show that the
European _Hipparion_ is rather a member of a collateral branch, than a
form in the direct line of succession. Next, in the backward order in
time, is the _Miohippus_, which corresponds pretty nearly with the
_Anchitherium_ of Europe. It presents three complete toes--one large
median and two smaller lateral ones; and there is a rudiment of that
digit, which answers to the little finger of the human hand.
The European record of the pedigree of the horse stops here; in the
American Tertiaries, on the contrary, the series of ancestral equine
forms is continued into the Eocene formations. An older Miocene form,
termed _Mesohippus_, has three toes in front, with a large splint-like
rudiment representing the little finger; and three toes behind. The
radius and ulna, the tibia and the fibula, are distinct, and the short
crowned molar teeth are anchitherioid in pattern.
But the most important discovery of all is the _Orohippus_, which comes
from the Eocene formation, and is the oldest member of the equine
series, as yet known. Here we find four complete toes on the front-limb,
three toes on the hind-limb, a well-developed ulna, a well-developed
fibula, and short-crowned grinders of simple pattern.
Thus, thanks to these important researches, it has become evident that,
so far as our present knowledge extends, the history of the horse-type
is exactly and precisely that which could have been predicted from a
knowledge of the principles of evolution. And the knowledge we now
possess justifies us completely in the anticipation, that when the still
lower Eocene deposits, and those which belong to the Cretaceous epoch,
have yielded up their remains of ancestral equine animals, we shall
find, first, a form with four complete toes and a rudiment of the
innermost or first digit in front, with, probably, a rudiment of the
fifth digit in the hind foot;[3] while, in still older forms, the series
of the digits will be more and more complete, until we come to the
five-toed animals, in which, if the doctrine of evolution is well
founded, the whole series must have taken its origin.
* * * * *
That is what I mean by demonstrative evidence of evolution. An inductive
hypothesis is said to be demonstrated when the facts are shown to be in
entire accordance with it. If that is not scientific proof, there are no
merely inductive conclusions which can be said to be proved. And the
doctrine of evolution, at the present time, rests upon exactly as secure
a foundation as the Copernican theory of the motions of the heavenly
bodies did at the time of its promulgation. Its logical basis is
precisely of the same character--the coincidence of the observed facts
with theoretical requirements.
The only way of escape, if it be a way of escape, from the conclusions
which I have just indicated, is the supposition that all these different
equine forms have been created separately at separate epochs of time;
and, I repeat, that of such an hypothesis as this there neither is, nor
can be, any scientific evidence; and, assuredly, so far as I know, there
is none which is supported, or pretends to be supported, by evidence or
authority of any other kind. I can but think that the time will come
when such suggestions as these, such obvious attempts to escape the
force of demonstration, will be put upon the same footing as the
supposition made by some writers, who are, I believe, not completely
extinct at present, that fossils are mere simulacra, are no indications
of the former existence of the animals to which they seem to belong; but
that they are either sports of Nature, or special creations,
intended--as I heard suggested the other day--to test our faith.
In fact, the whole evidence is in favour of evolution, and there is none
against it. And I say this, although perfectly well aware of the seeming
difficulties which have been built up upon what appears to the
uninformed to be a solid foundation. I meet constantly with the argument
that the doctrine of evolution cannot be well founded, because it
requires the lapse of a very vast period of time; the duration of life
upon the earth, thus implied, is inconsistent with the conclusions
arrived at by the astronomer and the physicist. I may venture to say
that I am familiar with those conclusions, inasmuch as some years ago,
when President of the Geological Society of London, I took the liberty
of criticising them, and of showing in what respects, as it appeared to
me, they lacked complete and thorough demonstration. But, putting that
point aside, suppose that, as the astronomers, or some of them, and some
physical philosophers, tell us, it is impossible that life could have
endured upon the earth for as long a period as is required by the
doctrine of evolution--supposing that to be proved--I desire to be
informed, what is the foundation for the statement that evolution does
require so great a time? The biologist knows nothing whatever of the
amount of time which may be required for the process of evolution. It is
a matter of fact that the equine forms which I have described to you
occur, in the order stated, in the Tertiary formations. But I have not
the slightest means of guessing whether it took a million of years, or
ten millions, or a hundred millions, or a thousand millions of years, to
give rise to that series of changes. A biologist has no means of
arriving at any conclusion as to the amount of time which may be needed
for a certain quantity of organic change. He takes his time from the
geologist. The geologist, considering the rate at which deposits are
formed and the rate at which denudation goes on upon the surface of the
earth, arrives at more or less justifiable conclusions as to the time
which is required for the deposit of a certain thickness of rocks; and
if he tells me that the Tertiary formations required 500,000,000 years
for their deposit, I suppose he has good ground for what he says, and I
take that as a measure of the duration of the evolution of the horse
from the _Orohippus_ up to its present condition. And, if he is right,
undoubtedly evolution is a very slow process, and requires a great deal
of time. But suppose, now, that an astronomer or a physicist--for
instance, my friend Sir William Thomson--tells me that my geological
authority is quite wrong; and that he has weighty evidence to show that
life could not possibly have existed upon the surface of the earth
500,000,000 years ago, because the earth would have then been too hot to
allow of life, my reply is: "That is not my affair; settle that with the
geologist, and when you have come to an agreement among yourselves I
will adopt your conclusion." We take our time from the geologists and
physicists; and it is monstrous that, having taken our time from the
physical philosopher's clock, the physical philosopher should turn round
upon us, and say we are too fast or too slow. What we desire to know is,
is it a fact that evolution took place? As to the amount of time which
evolution may have occupied, we are in the hands of the physicist and
the astronomer, whose business it is to deal with those questions.
* * * * *
I have now, ladies and gentlemen, arrived at the conclusion of the task
which I set before myself when I undertook to deliver these lectures. My
purpose has been, not to enable those among you who have paid no
attention to these subjects before, to leave this room in a condition to
decide upon the validity or the invalidity of the hypothesis of
evolution; but I have desired to put before you the principles upon
which all hypotheses respecting the history of Nature must be judged;
and furthermore, to make apparent the nature of the evidence and the
amount of cogency which is to be expected and may be obtained from it.
To this end, I have not hesitated to regard you as genuine students and
persons desirous of knowing the truth. I have not shrunk from taking you
through long discussions, that I fear may have sometimes tried your
patience; and I have inflicted upon you details which were
indispensable, but which may well have been wearisome. But I shall
rejoice--I shall consider that I have done you the greatest service,
which it was in my power to do--if I have thus convinced you that the
great question which we have been discussing is not one to be dealt with
by rhetorical flourishes, or by loose and superficial talk; but that it
requires the keen attention of the trained intellect and the patience of
the accurate observer.
When I commenced this series of lectures, I did not think it necessary
to preface them with a prologue, such as might be expected from a
stranger and a foreigner; for during my brief stay in your country, I
have found it very hard to believe that a stranger could be possessed of
so many friends, and almost harder that a foreigner could express
himself in your language in such a way as to be, to all appearance, so
readily intelligible. So far as I can judge, that most intelligent, and,
perhaps, I may add, most singularly active and enterprising body, your
press reporters, do not seem to have been deterred by my accent from
giving the fullest account of everything that I happen to have said.
But the vessel in which I take my departure to-morrow morning is even
now ready to slip her moorings; I awake from my delusion that I am other
than a stranger and a foreigner. I am ready to go back to my place and
country; but, before doing so, let me, by way of epilogue, tender to you
my most hearty thanks for the kind and cordial reception which you have
accorded to me; and let me thank you still more for that which is the
greatest compliment which can be afforded to any person in my
position--the continuous and undisturbed attention which you have
bestowed upon the long argument which I have had the honour to lay
before you.
[1] The absence of any keel on the breast-bone and some other
osteological peculiarities, observed by Professor Marsh,
however, suggest that _Hesperornis_ may be a modification of a
less specialised group of birds than that to which these
existing aquatic birds belong.
[2] I use the word "type" because it is highly probable that many
forms of _Anchitherium_-like and _Hipparion_-like animals
existed in the Miocene and Pliocene epochs, just as many species
of the horse tribe exist now; and it is highly improbable that
the particular species of _Anchitherium_ or _Hipparion_, which
happen to have been discovered, should be precisely those which
have formed part of the direct line of the horse's pedigree.
[3] Since this lecture was delivered, Professor Marsh has discovered
a new genus of equine mammals (_Eohippus_) from the lowest
Eocene deposits of the West, which corresponds very nearly to
this description.--_American Journal of Science_, November,
1876.
BALTIMORE.
ADDRESS ON UNIVERSITY EDUCATION.[1]
The actual work of the University founded in this city by the
well-considered munificence of Johns Hopkins commences to-morrow, and
among the many marks of confidence and good-will which have been
bestowed upon me in the United States, there is none which I value more
highly than that conferred by the authorities of the University when
they invited me to deliver an address on such an occasion.
For the event which has brought us together is, in many respects,
unique. A vast property is handed over to an administrative body,
hampered by no conditions save these;--That the principal shall not be
employed in building: that the funds shall be appropriated, in equal
proportions, to the promotion of natural knowledge and to the
alleviation of the bodily sufferings of mankind; and, finally, that
neither political nor ecclesiastical sectarianism shall be permitted to
disturb the impartial distribution of the testator's benefactions.
In my experience of life a truth which sounds very much like a paradox
has often asserted itself; namely, that a man's worst difficulties begin
when he is able to do as he likes. So long as a man is struggling with
obstacles he has an excuse for failure or shortcoming; but when fortune
removes them all and gives him the power of doing as he thinks best,
then comes the time of trial. There is but one right, and the
possibilities of wrong are infinite. I doubt not that the trustees of
the Johns Hopkins University felt the full force of this truth when they
entered on the administration of their trust a year and a half ago; and
I can but admire the activity and resolution which have enabled them,
aided by the able president whom they have selected, to lay down the
great outlines of their plan, and carry it thus far into execution. It
is impossible to study that plan without perceiving that great care,
forethought, and sagacity, have been bestowed upon it, and that it
demands the most respectful consideration. I have been endeavouring to
ascertain how far the principles which underlie it are in accordance
with those which have been established in my own mind by much and
long-continued thought upon educational questions. Permit me to place
before you the result of my reflections.
Under one aspect a university is a particular kind of educational
institution, and the views which we may take of the proper nature of a
university are corollaries from those which we hold respecting education
in general. I think it must be admitted that the school should prepare
for the university, and that the university should crown the edifice,
the foundations of which are laid in the school. University education
should not be something distinct from elementary education, but should
be the natural outgrowth and development of the latter. Now I have a
very clear conviction as to what elementary education ought to be; what
it really may be, when properly organised; and what I think it will be,
before many years have passed over our heads, in England and in America.
Such education should enable an average boy of fifteen or sixteen to
read and write his own language with ease and accuracy, and with a sense
of literary excellence derived from the study of our classic writers: to
have a general acquaintance with the history of his own country and with
the great laws of social existence; to have acquired the rudiments of
the physical and psychological sciences, and a fair knowledge of
elementary arithmetic and geometry. He should have obtained an
acquaintance with logic rather by example than by precept; while the
acquirement of the elements of music and drawing should have been
pleasure rather than work.
It may sound strange to many ears if I venture to maintain the
proposition that a young person, educated thus far, has had a liberal,
though perhaps not a full, education. But it seems to me that such
training as that to which I have referred may be termed liberal, in both
the senses in which that word is employed, with perfect accuracy. In the
first place, it is liberal in breadth. It extends over the whole ground
of things to be known and of faculties to be trained, and it gives equal
importance to the two great sides of human activity--art and science. In
the second place, it is liberal in the sense of being an education
fitted for free men; for men to whom every career is open, and from whom
their country may demand that they should be fitted to perform the
duties of any career. I cannot too strongly impress upon you the fact
that, with such a primary education as this, and with no more than is to
be obtained by building strictly upon its lines, a man of ability may
become a great writer or speaker, a statesman, a lawyer, a man of
science, painter, sculptor, architect, or musician. That even
development of all a man's faculties, which is what properly constitutes
culture, may be effected by such an education, while it opens the way
for the indefinite strengthening of any special capabilities with which
he may be gifted.
In a country like this, where most men have to carve out their own
fortunes and devote themselves early to the practical affairs of life,
comparatively few can hope to pursue their studies up to, still less
beyond, the age of manhood. But it is of vital importance to the welfare
of the community that those who are relieved from the need of making a
livelihood, and still more, those who are stirred by the divine impulses
of intellectual thirst or artistic genius, should be enabled to devote
themselves to the higher service of their kind, as centres of
intelligence, interpreters of nature, or creators of new forms of
beauty. And it is the function of a university to furnish such men with
the means of becoming that which it is their privilege and duty to be.
To this end the university need cover no ground foreign to that occupied
by the elementary school. Indeed it cannot; for the elementary
instruction which I have referred to embraces all the kinds of real
knowledge and mental activity possible to man. The university can add no
new departments of knowledge, can offer no new fields of mental
activity; but what it can do is to intensify and specialise the
instruction in each department. Thus literature and philology,
represented in the elementary school by English alone, in the university
will extend over the ancient and modern languages. History, which, like
charity, best begins at home, but, like charity, should not end there,
will ramify into anthropology, archæology, political history, and
geography, with the history of the growth of the human mind and of its
products in the shape of philosophy, science, and art. And the
university will present to the student libraries, museums of
antiquities, collections of coins, and the like, which will efficiently
subserve these studies. Instruction in the elements of social economy, a
most essential, but hitherto sadly-neglected part of elementary
education, will develop in the university into political economy,
sociology, and law. Physical science will have its great divisions of
physical geography, with geology and astronomy; physics; chemistry and
biology; represented not merely by professors and their lectures, but by
laboratories, in which the students, under guidance of demonstrators,
will work out facts for themselves and come into that direct contact
with reality which constitutes the fundamental distinction of scientific
education. Mathematics will soar into its highest regions; while the
high peaks of philosophy may be scaled by those whose aptitude for
abstract thought has been awakened by elementary logic. Finally, schools
of pictorial and plastic art, of architecture, and of music, will offer
a thorough discipline in the principles and practice of art to those in
whom lies nascent the rare faculty of æsthetic representation, or the
still rarer powers of creative genius.
The primary school and the university are the alpha and omega of
education. Whether institutions intermediate between these (so-called
secondary schools) should exist, appears to me to be a question of
practical convenience. If such schools are established, the important
thing is that they should be true intermediaries between the primary
school and the university, keeping on the wide track of general culture,
and not sacrificing one branch of knowledge for another.
Such appear to me to be the broad outlines of the relations which the
university, regarded as a place of education, ought to bear to the
school, but a number of points of detail require some consideration,
however briefly and imperfectly I can deal with them. In the first
place, there is the important question of the limitations which should
be fixed to the entrance into the university; or, what qualifications
should be required of those who propose to take advantage of the higher
training offered by the university. On the one hand, it is obviously
desirable that the time and opportunities of the university should not
be wasted in conferring such elementary instruction as can be obtained
elsewhere; while, on the other hand, it is no less desirable that the
higher instruction of the university should be made accessible to every
one who can take advantage of it, although he may not have been able to
go through any very extended course of education. My own feeling is
distinctly against any absolute and defined preliminary examination, the
passing of which shall be an essential condition of admission to the
university. I would admit to the university any one who could be
reasonably expected to profit by the instruction offered to him; and I
should be inclined, on the whole, to test the fitness of the student,
not by examination before he enters the university, but at the end of
his first term of study. If, on examination in the branches of knowledge
to which he has devoted himself, he show himself deficient in industry
or in capacity, it will be best for the university and best for himself,
to prevent him from pursuing a vocation for which he is obviously unfit.
And I hardly know of any other method than this by which his fitness or
unfitness can be safely ascertained, though no doubt a good deal may be
done, not by formal cut and dried examination, but by judicious
questioning, at the outset of his career.
Another very important and difficult practical question is, whether a
definite course of study shall be laid down for those who enter the
university; whether a curriculum shall be prescribed; or whether the
student shall be allowed to range at will among the subjects which are
open to him. And this question is inseparably connected with another,
namely, the conferring of degrees. It is obviously impossible that any
student should pass through the whole of the series of courses of
instruction offered by a university. If a degree is to be conferred as a
mark of proficiency in knowledge, it must be given on the ground that
the candidate is proficient in a certain fraction of those studies; and
then will arise the necessity of insuring an equivalency of degrees, so
that the course by which a degree is obtained shall mark approximately
an equal amount of labour and of acquirements, in all cases. But this
equivalency can hardly be secured in any other way than by prescribing a
series of definite lines of study. This is a matter which will require
grave consideration. The important points to bear in mind, I think, are
that there should not be too many subjects in the curriculum, and that
the aim should be the attainment of thorough and sound knowledge of
each.
One half of the Johns Hopkins bequest is devoted to the establishment of
a hospital, and it was the desire of the testator that the university
and the hospital should co-operate in the promotion of medical
education. The trustees will unquestionably take the best advice that is
to be had as to the construction and administration of the hospital. In
respect to the former point, they will doubtless remember that a
hospital may be so arranged as to kill more than it cures; and, in
regard to the latter, that a hospital may spread the spirit of pauperism
among the well-to-do, as well as relieve the sufferings of the
destitute. It is not for me to speak on these topics--rather let me
confine myself to the one matter on which my experience as a student of
medicine, and an examiner of long standing, who has taken a great
interest in the subject of medical education, may entitle me to a
hearing. I mean the nature of medical education itself, and the
co-operation of the university in its promotion.
What is the object of medical education? It is to enable the
practitioner, on the one hand, to prevent disease by his knowledge of
hygiene; on the other hand, to divine its nature, and to alleviate or
cure it, by his knowledge of pathology, therapeutics, and practical
medicine. That is his business in life, and if he has not a thorough and
practical knowledge of the conditions of health, of the causes which
tend to the establishment of disease, of the meaning of symptoms, and of
the uses of medicines and operative appliances, he is incompetent, even
if he were the best anatomist, or physiologist, or chemist, that ever
took a gold medal or won a prize certificate. This is one great truth
respecting medical education. Another is, that all practice in medicine
is based upon theory of some sort or other; and therefore, that it is
desirable to have such theory in the closest possible accordance with
fact. The veriest empiric who gives a drug in one case because he has
seen it do good in another of apparently the same sort, acts upon the
theory that similarity of superficial symptoms means similarity of
lesions; which, by the way, is perhaps as wild an hypothesis as could be
invented. To understand the nature of disease we must understand health,
and the understanding of the healthy body means the having a knowledge
of its structure and of the way in which its manifold actions are
performed, which is what is technically termed human anatomy and human
physiology. The physiologist again must needs possess an acquaintance
with physics and chemistry, inasmuch as physiology is, to a great
extent, applied physics and chemistry. For ordinary purposes a limited
amount of such knowledge is all that is needful; but for the pursuit of
the higher branches of physiology no knowledge of these branches of
science can be too extensive, or too profound. Again, what we call
therapeutics, which has to do with the action of drugs and medicines on
the living organism, is, strictly speaking, a branch of experimental
physiology, and is daily receiving a greater and greater experimental
development.
The third great fact which is to be taken into consideration in dealing
with medical education, is that the practical necessities of life do
not, as a rule, allow aspirants to medical practice to give more than
three, or it may be four years to their studies. Let us put it at four
years, and then reflect that, in the course of this time, a young man
fresh from school has to acquaint himself with medicine, surgery,
obstetrics, therapeutics, pathology, hygiene, as well as with the
anatomy and the physiology of the human body; and that his knowledge
should be of such a character that it can be relied upon in any
emergency, and always ready for practical application. Consider, in
addition, that the medical practitioner may be called upon, at any
moment, to give evidence in a court of justice in a criminal case; and
that it is therefore well that he should know something of the laws of
evidence, and of what we call medical jurisprudence. On a medical
certificate, a man may be taken from his home and from his business and
confined in a lunatic asylum; surely, therefore, it is desirable that
the medical practitioner should have some rational and clear conceptions
as to the nature and symptoms of mental disease. Bearing in mind all
these requirements of medical education, you will admit that the burden
on the young aspirant for the medical profession is somewhat of the
heaviest, and that it needs some care to prevent his intellectual back
from being broken.
Those who are acquainted with the existing systems of medical education
will observe that, long as is the catalogue of studies which I have
enumerated, I have omitted to mention several that enter into the usual
medical curriculum of the present day. I have said not a word about
zoology, comparative anatomy, botany, or materia medica. Assuredly this
is from no light estimate of the value or importance of such studies in
themselves. It may be taken for granted that I should be the last person
in the world to object to the teaching of zoology, or comparative
anatomy, in themselves; but I have the strongest feeling that,
considering the number and the gravity of those studies through which a
medical man must pass, if he is to be competent to discharge the serious
duties which devolve upon him, subjects which lie so remote as these do
from his practical pursuits should be rigorously excluded. The young
man, who has enough to do in order to acquire such familiarity with the
structure of the human body as will enable him to perform the operations
of surgery, ought not, in my judgment, to be occupied with
investigations into the anatomy of crabs and starfishes. Undoubtedly the
doctor should know the common poisonous plants of his own country when
he sees them; but that knowledge may be obtained by a few hours devoted
to the examination of specimens of such plants, and the desirableness of
such knowledge is no justification, to my mind, for spending three
months over the study of systematic botany. Again, materia medica, so
far as it is a knowledge of drugs, is the business of the druggist. In
all other callings the necessity of the division of labour is fully
recognised, and it is absurd to require of the medical man that he
should not avail himself of the special knowledge of those whose
business it is to deal in the drugs which he uses. It is all very well
that the physician should know that castor oil comes from a plant, and
castoreum from an animal, and how they are to be prepared; but for all
the practical purposes of his profession that knowledge is not of one
whit more value, has no more relevancy, than the knowledge of how the
steel of his scalpel is made.
All knowledge is good. It is impossible to say that any fragment of
knowledge, however insignificant or remote from one's ordinary pursuits,
may not some day be turned to account. But in medical education, above
all things, it is to be recollected that, in order to know a little
well, one must be content to be ignorant of a great deal.
Let it not be supposed that I am proposing to narrow medical education,
or, as the cry is, to lower the standard of the profession. Depend upon
it there is only one way of really ennobling any calling, and that is to
make those who pursue it real masters of their craft, men who can truly
do that which they profess to be able to do, and which they are credited
with being able to do by the public. And there is no position so ignoble
as that of the so-called "liberally-educated practitioner," who, as
Talleyrand said of his physician, "Knows everything, even a little
physic;" who may be able to read Galen in the original; who knows all
the plants, from the cedar of Lebanon to the hyssop upon the wall; but
who finds himself, with the issues of life and death in his hands,
ignorant, blundering, and bewildered, because of his ignorance of the
essential and fundamental truths upon which practice must be based.
Moreover, I venture to say, that any man who has seriously studied all
the essential branches of medical knowledge; who has the needful
acquaintance with the elements of physical science; who has been brought
by medical jurisprudence into contact with law; whose study of insanity
has taken him into the fields of psychology; has _ipso facto_ received a
liberal education.
Having lightened the medical curriculum by culling out of it everything
which is unessential, we may next consider whether something may not be
done to aid the medical student toward the acquirement of real knowledge
by modifying the system of examination. In England, within my
recollection, it was the practice to require of the medical student
attendance on lectures upon the most diverse topics during three years;
so that it often happened that he would have to listen, in the course of
a day, to four or five lectures upon totally different subjects, in
addition to the hours given to dissection and to hospital practice: and
he was required to keep all the knowledge he could pick up, in this
distracting fashion, at examination point, until, at the end of three
years, he was set down to a table and questioned pell-mell upon all the
different matters with which he had been striving to make acquaintance.
A worse system and one more calculated to obstruct the acquisition of
sound knowledge and to give full play to the "crammer" and the "grinder"
could hardly have been devised by human ingenuity. Of late years great
reforms have taken place. Examinations have been divided so as to
diminish the number of subjects among which the attention has to be
distributed. Practical examination has been largely introduced; but
there still remains, even under the present system, too much of the old
evil inseparable from the contemporaneous pursuit of a multiplicity of
diverse studies.
Proposals have recently been made to get rid of general examinations
altogether, to permit the student to be examined in each subject at the
end of his attendance on the class; and then, in case of the result
being satisfactory, to allow him to have done with it; and I may say
that this method has been pursued for many years in the Royal School of
Mines in London, and has been found to work very well. It allows the
student to concentrate his mind upon what he is about for the time
being, and then to dismiss it. Those who are occupied in intellectual
work, will, I think, agree with me that it is important, not so much to
know a thing, as to have known it, and known it thoroughly. If you have
once known a thing in this way it is easy to renew your knowledge when
you have forgotten it; and when you begin to take the subject up again,
it slides back upon the familiar grooves with great facility.
Lastly comes the question as to how the university may co-operate in
advancing medical education. A medical school is strictly a technical
school--a school in which a practical profession is taught--while a
university ought to be a place in which knowledge is obtained without
direct reference to professional purposes. It is clear, therefore, that
a university and its antecedent, the school, may best co-operate with
the medical school by making due provision for the study of those
branches of knowledge which lie at the foundation of medicine.
At present, young men come to the medical schools without a conception
of even the elements of physical science; they learn, for the first
time, that there are such sciences as physics, chemistry, and
physiology, and are introduced to anatomy as a new thing. It may be
safely said that, with a large proportion of medical students, much of
the first session is wasted in learning how to learn--in familiarising
themselves with utterly strange conceptions, and in awakening their
dormant and wholly untrained powers of observation and of manipulation.
It is difficult to overestimate the magnitude of the obstacles which are
thrown in the way of scientific training by the existing system of
school education. Not only are men trained in mere book-work, ignorant
of what observation means, but the habit of learning from books alone
begets a disgust of observation. The book-learned student will rather
trust to what he sees in a book than to the witness of his own eyes.
There is not the least reason why this should be so, and, in fact, when
elementary education becomes that which I have assumed it ought to be,
this state of things will no longer exist. There is not the slightest
difficulty in giving sound elementary instruction in physics, in
chemistry, and in the elements of human physiology, in ordinary schools.
In other words, there is no reason why the student should not come to
the medical school, provided with as much knowledge of these several
sciences as he ordinarily picks up, in the course of his first year of
attendance, at the medical school.
I am not saying this without full practical justification for the
statement. For the last eighteen years we have had in England a system
of elementary science teaching carried out under the auspices of the
Science and Art Department, by which elementary scientific instruction
is made readily accessible to the scholars of all the elementary schools
in the country. Commencing with small beginnings, carefully developed
and improved, that system now brings up for examination as many as seven
thousand scholars in the subject of human physiology alone. I can say
that, out of that number, a large proportion have acquired a fair amount
of substantial knowledge; and that no inconsiderable percentage show as
good an acquaintance with human physiology as used to be exhibited by
the average candidates for medical degrees in the University of London,
when I was first an examiner there twenty years ago; and quite as much
knowledge as is possessed by the ordinary student of medicine at the
present day. I am justified, therefore, in looking forward to the time
when the student who proposes to devote himself to medicine will come,
not absolutely raw and inexperienced as he is at present, but in a
certain state of preparation for further study; and I look to the
university to help him still further forward in that stage of
preparation, through the organisation of its biological department. Here
the student will find means of acquainting himself with the phenomena of
life in their broadest acceptation. He will study not botany and
zoology, which, as I have said, would take him too far away from his
ultimate goal; but, by duly arranged instruction, combined with work in
the laboratory upon the leading types of animal and vegetable life, he
will lay a broad, and at the same time solid, foundation of biological
knowledge; he will come to his medical studies with a comprehension of
the great truths of morphology and of physiology, with his hands trained
to dissect and his eyes taught to see. I have no hesitation in saying
that such preparation is worth a full year added on to the medical
curriculum. In other words, it will set free that much time for
attention to those studies which bear directly upon the student's most
grave and serious duties as a medical practitioner.
Up to this point I have considered only the teaching aspect of your
great foundation, that function of the university in virtue of which it
plays the part of a reservoir of ascertained truth, so far as our
symbols can ever interpret nature. All can learn; all can drink of this
lake. It is given to few to add to the store of knowledge, to strike new
springs of thought, or to shape new forms of beauty. But so sure as it
is that men live not by bread, but by ideas, so sure is it that the
future of the world lies in the hands of those who are able to carry the
interpretation of nature a step further than their predecessors; so
certain is it that the highest function of a university is to seek out
those men, cherish them, and give their ability to serve their kind full
play.
I rejoice to observe that the encouragement of research occupies so
prominent a place in your official documents, and in the wise and
liberal inaugural address of your president. This subject of the
encouragement, or, as it is sometimes called, the endowment of research,
has of late years greatly exercised the minds of men in England. It was
one of the main topics of discussion by the members of the Royal
Commission of whom I was one, and who not long since issued their
report, after five years' labour. Many seem to think that this question
is mainly one of money; that you can go into the market and buy
research, and that supply will follow demand, as in the ordinary course
of commerce. This view does not commend itself to my mind. I know of no
more difficult practical problem than the discovery of a method of
encouraging and supporting the original investigator without opening the
door to nepotism and jobbery. My own conviction is admirably summed up
in the passage of your president's address, "that the best investigators
are usually those who have also the responsibilities of instruction,
gaining thus the incitement of colleagues, the encouragement of pupils,
and the observation of the public."
At the commencement of this address I ventured to assume that I might,
if I thought fit, criticise the arrangements which have been made by the
board of trustees, but I confess that I have little to do but to applaud
them. Most wise and sagacious seems to me the determination not to build
for the present. It has been my fate to see great educational funds
fossilise into mere bricks and mortar, in the petrifying springs of
architecture, with nothing left to work the institution they were
intended to support. A great warrior is said to have made a desert and
called it peace. Administrators of educational funds have sometimes made
a palace and called it a university. If I may venture to give advice in
a matter which lies out of my proper competency, I would say that
whenever you do build, get an honest bricklayer, and make him build you
just such rooms as you really want, leaving ample space for expansion.
And a century hence, when the Baltimore and Ohio shares are at one
thousand premium, and you have endowed all the professors you need, and
built all the laboratories that are wanted, and have the best museum and
the finest library that can be imagined; then, if you have a few hundred
thousand dollars you don't know what to do with, send for an architect
and tell him to put up a façade. If American is similar to English
experience, any other course will probably lead you into having some
stately structure, good for your architect's fame, but not in the least
what you want.
It appears to me that what I have ventured to lay down as the principles
which should govern the relations of a university to education in
general, are entirely in accordance with the measures you have adopted.
You have set no restrictions upon access to the instruction you propose
to give; you have provided that such instruction, either as given by the
university or by associated institutions, should cover the field of
human intellectual activity. You have recognised the importance of
encouraging research. You propose to provide means by which young men,
who may be full of zeal for a literary or for a scientific career, but
who also may have mistaken aspiration for inspiration, may bring their
capacities to a test, and give their powers a fair trial. If such a one
fail, his endowment terminates, and there is no harm done. If he
succeed, you may give power of flight to the genius of a Davy or a
Faraday, a Carlyle or a Locke, whose influence on the future of his
fellow-men shall be absolutely incalculable.
You have enunciated the principle that "the glory of the university
should rest upon the character of the teachers and scholars, and not
upon their numbers or buildings constructed for their use." And I look
upon it as an essential and most important feature of your plan that the
income of the professors and teachers shall be independent of the number
of students whom they can attract. In this way you provide against the
danger, patent elsewhere, of finding attempts at improvement obstructed
by vested interests; and, in the department of medical education
especially, you are free of the temptation to set loose upon the world
men utterly incompetent to perform the serious and responsible duties of
their profession.
It is a delicate matter for a stranger to the practical working of your
institutions, like myself, to pretend to give an opinion as to the
organisation of your governing power. I can conceive nothing better than
that it should remain as it is, if you can secure a succession of wise,
liberal, honest, and conscientious men to fill the vacancies that occur
among you. I do not greatly believe in the efficacy of any kind of
machinery for securing such a result; but I would venture to suggest
that the exclusive adoption of the method of co-optation for filling the
vacancies which must occur in your body, appears to me to be somewhat
like a tempting of Providence. Doubtless there are grave practical
objections to the appointment of persons outside of your body and not
directly interested in the welfare of the university; but might it not
be well if there were an understanding that your academic staff should
be officially represented on the board, perhaps even the heads of one or
two independent learned bodies, so that academic opinion and the views
of the outside world might have a certain influence in that most
important matter, the appointment of your professors? I throw out these
suggestions, as I have said, in ignorance of the practical difficulties
that may lie in the way of carrying them into effect, on the general
ground that personal and local influences are very subtle, and often
unconscious, while the future greatness and efficiency of the noble
institution which now commences its work must largely depend upon its
freedom from them.
* * * * *
I constantly hear Americans speak of the charm which our old mother
country has for them, of the delight with which they wander through the
streets of ancient towns, or climb the battlements of mediæval
strongholds, the names of which are indissolubly associated with the
great epochs of that noble literature which is our common inheritance;
or with the blood-stained steps of that secular progress, by which the
descendants of the savage Britons and of the wild pirates of the North
Sea have become converted into warriors of order and champions of
peaceful freedom, exhausting what still remains of the old Berserk
spirit in subduing nature, and turning the wilderness into a garden. But
anticipation has no less charm than retrospect, and to an Englishman
landing upon your shores for the first time, travelling for hundreds of
miles through strings of great and well-ordered cities, seeing your
enormous actual, and almost infinite potential, wealth in all
commodities, and in the energy and ability which turn wealth to account,
there is something sublime in the vista of the future. Do not suppose
that I am pandering to what is commonly understood by national pride. I
cannot say that I am in the slightest degree impressed by your bigness,
or your material resources, as such. Size is not grandeur, and territory
does not make a nation. The great issue, about which hangs a true
sublimity, and the terror of overhanging fate, is what are you going to
do with all these things? What is to be the end to which these are to be
the means? You are making a novel experiment in politics on the greatest
scale which the world has yet seen. Forty millions at your first
centenary, it is reasonably to be expected that, at the second, these
states will be occupied by two hundred millions of English-speaking
people, spread over an area as large as that of Europe, and with
climates and interests as diverse as those of Spain and Scandinavia,
England and Russia. You and your descendants have to ascertain whether
this great mass will hold together under the forms of a republic, and
the despotic reality of universal suffrage; whether state rights will
hold out against centralisation, without separation; whether
centralisation will get the better, without actual or disguised
monarchy; whether shifting corruption is better than a permanent
bureaucracy; and as population thickens in your great cities, and the
pressure of want is felt, the gaunt spectre of pauperism will stalk
among you, and communism and socialism will claim to be heard. Truly
America has a great future before her; great in toil, in care, and in
responsibility; great in true glory if she be guided in wisdom and
righteousness; great in shame if she fail. I cannot understand why other
nations should envy you, or be blind to the fact that it is for the
highest interest of mankind that you should succeed; but the one
condition of success, your sole safeguard, is the moral worth and
intellectual clearness of the individual citizen. Education cannot give
these, but it may cherish them and bring them to the front in whatever
station of society they are to be found; and the universities ought to
be, and may be, the fortresses of the higher life of the nation.
May the university which commences its practical activity to-morrow
abundantly fulfil its high purpose; may its renown as a seat of true
learning, a centre of free inquiry, a focus of intellectual light,
increase year by year, until men wander hither from all parts of the
earth, as of old they sought Bologna, or Paris, or Oxford.
And it is pleasant to me to fancy that, among the English students who
are drawn to you at that time, there may linger a dim tradition that a
countryman of theirs was permitted to address you as he has done to-day,
and to feel as if your hopes were his hopes and your success his joy.
[1] Delivered at the formal opening of the Johns Hopkins University
at Baltimore, U.S., September 12. The total amount bequeathed by
Johns Hopkins is more than 7,000,000 dollars. The sum of
3,500,000 dollars is appropriated to a university, a like sum to
a hospital, and the rest to local institutions of education and
charity.
LONDON.
LECTURE ON THE STUDY OF BIOLOGY.
It is my duty to-night to speak about the study of Biology, and while it
may be that there are many of my audience who are quite familiar with
that study, yet as a lecturer of some standing, it would, I know by
experience, be very bad policy on my part to suppose such to be
extensively the case. On the contrary, I must imagine that there are
many of you who would like to know what Biology is; that there are
others who have that amount of information, but would nevertheless
gladly hear why it should be worth their while to study Biology; and yet
others, again, to whom these two points are clear, but who desire to
learn how they had best study it, and, finally, when they had best study
it.
I shall, therefore, address myself to the endeavour to give you some
answer to these four questions--what Biology is; why it should be
studied; how it should be studied; and when it should be studied.
In the first place, in respect to what Biology is, there are, I believe,
some persons who imagine that the term "Biology" is simply a new-fangled
denomination, a neologism in short, for what used to be known under the
title of "Natural History;" but I shall try to show you, on the
contrary, that the word is the expression of the growth of science
during the last 200 years, and came into existence half a century ago.
At the revival of learning, knowledge was divided into two kinds--the
knowledge of nature and the knowledge of man; for it was the current
idea then (and a great deal of that ancient conception still remains)
that there was a sort of essential antithesis, not to say antagonism,
between nature and man; and that the two had not very much to do with
one another, except that the one was oftentimes exceedingly troublesome
to the other. Though it is one of the salient merits of our great
philosophers of the seventeenth century, that they recognised but one
scientific method, applicable alike to man and to nature, we find this
notion of the existence of a broad distinction between nature and man in
the writings both of Bacon and of Hobbes of Malmesbury; and I have
brought with me that famous work which is now so little known, greatly
as it deserves to be studied, "The Leviathan," in order that I may put
to you in the wonderfully terse and clear language of Thomas Hobbes,
what was his view of the matter. He says:--
"The register of knowledge of fact is called history. Whereof there
be two sorts, one called natural history; which is the history of
such facts or effects of nature as have no dependence on man's
will; such as are the histories of metals, plants, animals,
regions, and the like. The other is civil history; which is the
history of the voluntary actions of men in commonwealths."
So that all history of fact was divided into these two great groups of
natural and of civil history. The Royal Society was in course of
foundation about the time that Hobbes was writing this book, which was
published in 1651; and that Society was termed a "Society for the
Improvement of Natural Knowledge," which was then nearly the same thing
as a "Society for the Improvement of Natural History." As time went on,
and the various branches of human knowledge became more distinctly
developed and separated from one another, it was found that some were
much more susceptible of precise mathematical treatment than others. The
publication of the "Principia" of Newton, which probably gave a greater
stimulus to physical science than any work ever published before, or
which is likely to be published hereafter, showed that precise
mathematical methods were applicable to those branches of science such
as astronomy, and what we now call physics, which occupy a very large
portion of the domain of what the older writers understood by natural
history. And inasmuch as the partly deductive and partly experimental
methods of treatment to which Newton and others subjected these branches
of human knowledge, showed that the phenomena of nature which belonged
to them were susceptible of explanation, and thereby came within the
reach of what was called "philosophy" in those days; so much of this
kind of knowledge as was not included under astronomy came to be spoken
of as "natural philosophy"--a term which Bacon had employed in a much
wider sense. Time went on, and yet other branches of science developed
themselves. Chemistry took a definite shape; and since all these
sciences, such as astronomy, natural philosophy, and chemistry, were
susceptible either of mathematical treatment or of experimental
treatment, or of both, a broad distinction was drawn between the
experimental branches of what had previously been called natural history
and the observational branches--those in which experiment was (or
appeared to be) of doubtful use, and where, at that time, mathematical
methods were inapplicable. Under these circumstances the old name of
"Natural History" stuck by the residuum, by those phenomena which were
not, at that time, susceptible of mathematical or experimental
treatment; that is to say, those phenomena of nature which come now
under the general heads of physical geography, geology, mineralogy, the
history of plants, and the history of animals. It was in this sense that
the term was understood by the great writers of the middle of the last
century--Buffon and Linnæus--by Buffon in his great work, the "Histoire
Naturelle Générale," and by Linnæus in his splendid achievement, the
"Systema Naturæ." The subjects they deal with are spoken of as "Natural
History," and they called themselves and were called "Naturalists." But
you will observe that this was not the original meaning of these terms;
but that they had, by this time, acquired a signification widely
different from that which they possessed primitively.
The sense in which "Natural History" was used at the time I am now
speaking of has, to a certain extent, endured to the present day. There
are now in existence in some of our northern universities, chairs of
"Civil and Natural History," in which "Natural History" is used to
indicate exactly what Hobbes and Bacon meant by that term. The unhappy
incumbent of the chair of Natural History is, or was, supposed to cover
the whole ground of geology, mineralogy, and zoology, perhaps even
botany, in his lectures.
But as science made the marvellous progress which it did make at the
latter end of the last and the beginning of the present century,
thinking men began to discern that under this title of "Natural History"
there were included very heterogeneous constituents--that, for example,
geology and mineralogy were, in many respects, widely different from
botany and zoology; that a man might obtain an extensive knowledge of
the structure and functions of plants and animals, without having need
to enter upon the study of geology or mineralogy, and _vice versâ_; and,
further as knowledge advanced, it became clear that there was a great
analogy, a very close alliance, between those two sciences of botany and
zoology which deal with living beings, while they are much more widely
separated from all other studies. It is due to Buffon to remark that he
clearly recognised this great fact. He says: "Ces deux genres d'êtres
organisés [les animaux et les végétaux] ont beaucoup plus de propriétés
communes que de différences réelles." Therefore, it is not wonderful
that, at the beginning of the present century, in two different
countries, and so far as I know, without any intercommunication, two
famous men clearly conceived the notion of uniting the sciences which
deal with living matter into one whole, and of dealing with them as one
discipline. In fact, I may say there were three men to whom this idea
occurred contemporaneously, although there were but two who carried it
into effect, and only one who worked it out completely. The persons to
whom I refer were the eminent physiologist Bichat, and the great
naturalist Lamarck, in France; and a distinguished German, Treviranus.
Bichat[1] assumed the existence of a special group of "physiological"
sciences. Lamarck, in a work published in 1801,[2] for the first time
made use of the name "Biologie" from the two Greek words which signify a
discourse upon life and living things. About the same time it occurred
to Treviranus, that all those sciences which deal with living matter are
essentially and fundamentally one, and ought to be treated as a whole;
and, in the year 1802, he published the first volume of what he also
called "Biologie." Treviranus's great merit lies in this, that he worked
out his idea, and wrote the very remarkable book to which I refer. It
consists of six volumes, and occupied its author for twenty years--from
1802 to 1822.
That is the origin of the term "Biology;" and that is how it has come
about that all clear thinkers and lovers of consistent nomenclature have
substituted for the old confusing name of "Natural History," which has
conveyed so many meanings, the term "Biology" which denotes the whole of
the sciences which deal with living things, whether they be animals or
whether they be plants. Some little time ago--in the course of this
year, I think--I was favoured by a learned classic, Dr. Field of
Norwich, with a disquisition, in which he endeavoured to prove that,
from a philological point of view, neither Treviranus nor Lamarck had
any right to coin this new word "Biology" for their purpose; that, in
fact, the Greek word "Bios" had relation only to human life and human
affairs, and that a different word was employed by the Greeks when they
wished to speak of the life of animals and plants. So Dr. Field tells us
we are all wrong in using the term biology, and that we ought to employ
another; only he is not quite sure about the propriety of that which he
proposes as a substitute. It is a somewhat hard one--"zootocology." I am
sorry we are wrong, because we are likely to continue so. In these
matters we must have some sort of "Statute of Limitations." When a name
has been employed for half-a-century, persons of authority[3] have been
using it, and its sense has become well understood, I am afraid that
people will go on using it, whatever the weight of philological
objection.
Now that we have arrived at the origin of this word "Biology," the next
point to consider is: What ground does it cover? I have said that, in
its strict technical sense, it denotes all the phenomena which are
exhibited by living things, as distinguished from those which are not
living; but while that is all very well, so long as we confine ourselves
to the lower animals and to plants, it lands us in considerable
difficulties when we reach the higher forms of living things. For
whatever view we may entertain about the nature of man, one thing is
perfectly certain, that he is a living creature. Hence, if our
definition is to be interpreted strictly, we must include man and all
his ways and works under the head of Biology; in which case, we should
find that psychology, politics, and political economy would be absorbed
into the province of Biology. In fact, civil history would be merged in
natural history. In strict logic it may be hard to object to this
course, because no one can doubt that the rudiments and outlines of our
own mental phenomena are traceable among the lower animals. They have
their economy and their polity, and if, as is always admitted, the
polity of bees and the commonwealth of wolves fall within the purview of
the biologist proper, it becomes hard to say why we should not include
therein human affairs, which in so many cases resemble those of the bees
in zealous getting, and are not without a certain parity in the
proceedings of the wolves. The real fact is that we biologists are a
self-sacrificing people; and inasmuch as, on a moderate estimate, there
are about a quarter of a million different species of animals and plants
to know about already, we feel that we have more than sufficient
territory. There has been a sort of practical convention by which we
give up to a different branch of science what Bacon and Hobbes would
have called "Civil History." That branch of science has constituted
itself under the head of Sociology. I may use phraseology which, at
present, will be well understood and say that we have allowed that
province of Biology to become autonomous; but I should like you to
recollect that that is a sacrifice, and that you should not be surprised
if it occasionally happens that you see a biologist apparently
trespassing in the region of philosophy or politics; or meddling with
human education; because, after all, that is a part of his kingdom which
he has only voluntarily forsaken.
Having now defined the meaning of the word Biology, and having indicated
the general scope of Biological Science, I turn to my second question,
which is--Why should we study Biology? Possibly the time may come when
that will seem a very odd question. That we, living creatures, should
not feel a certain amount of interest in what it is that constitutes our
life will eventually, under altered ideas of the fittest objects of
human inquiry, appear to be a singular phenomenon; but, at present,
judging by the practice of teachers and educators, Biology would seem to
be a topic that does not concern us at all. I propose to put before you
a few considerations with which I dare say many will be familiar
already, but which will suffice to show--not fully, because to
demonstrate this point fully would take a great many lectures--that
there are some very good and substantial reasons why it may be advisable
that we should know something about this branch of human learning.
I myself entirely agree with another sentiment of the philosopher of
Malmesbury, "that the scope of all speculation is the performance of
some action or thing to be done," and I have not any very great respect
for, or interest in, mere knowing as such. I judge of the value of human
pursuits by their bearing upon human interests; in other words, by their
utility; but I should like that we should quite clearly understand what
it is that we mean by this word "utility." In an Englishman's mouth it
generally means that by which we get pudding or praise, or both. I have
no doubt that is one meaning of the word utility, but it by no means
includes all I mean by utility. I think that knowledge of every kind is
useful in proportion as it tends to give people right ideas, which are
essential to the foundation of right practice, and to remove wrong
ideas, which are the no less essential foundations and fertile mothers
of every description of error in practice. And inasmuch as, whatever
practical people may say, this world is, after all, absolutely governed
by ideas, and very often by the wildest and most hypothetical ideas, it
is a matter of the very greatest importance that our theories of things,
and even of things that seem a long way apart from our daily lives,
should be as far as possible true, and as far as possible removed from
error. It is not only in the coarser practical sense of the word
"utility," but in this higher and broader sense, that I measure the
value of the study of biology by its utility; and I shall try to point
out to you that you will feel the need of some knowledge of biology at a
great many turns of this present nineteenth century life of ours. For
example, most of us attach great importance to the conception which we
entertain of the position of man in this universe and his relation to
the rest of nature. We have almost all been told, and most of us hold by
the tradition, that man occupies an isolated and peculiar position in
nature; that though he is in the world he is not of the world; that his
relations to things about him are of a remote character; that his origin
is recent, his duration likely to be short, and that he is the great
central figure round which other things in this world revolve. But this
is not what the biologist tells us.
At the present moment you will be kind enough to separate me from them,
because it is in no way essential to my present argument that I should
advocate their views. Don't suppose that I am saying this for the
purpose of escaping the responsibility of their beliefs; indeed, at
other times and in other places, I do not think that point has been left
doubtful; but I want clearly to point out to you that for my present
argument they may all be wrong; and, nevertheless, my argument will hold
good. The biologists tell us that all this is an entire mistake. They
turn to the physical organisation of man. They examine his whole
structure, his bony frame and all that clothes it. They resolve him into
the finest particles into which the microscope will enable them to break
him up. They consider the performance of his various functions and
activities, and they look at the manner in which he occurs on the
surface of the world. Then they turn to other animals, and taking the
first handy domestic animal--say a dog--they profess to be able to
demonstrate that the analysis of the dog leads them, in gross, to
precisely the same results as the analysis of the man; that they find
almost identically the same bones, having the same relations; that they
can name the muscles of the dog by the names of the muscles of the man,
and the nerves of the dog by those of the nerves of the man, and that,
such structures and organs of sense as we find in the man such also we
find in the dog; they analyse the brain and spinal cord, and they find
that the nomenclature which fits the one answers for the other. They
carry their microscopic inquiries in the case of the dog as far as they
can, and they find that his body is resolvable into the same elements as
those of the man. Moreover, they trace back the dog's and the man's
development, and they find that, at a certain stage of their existence,
the two creatures are not distinguishable the one from the other; they
find that the dog and his kind have a certain distribution over the
surface of the world, comparable in its way to the distribution of the
human species. What is true of the dog they tell us is true of all the
higher animals; and they assert that they can lay down a common plan for
the whole of these creatures, and regard the man and the dog, the horse
and the ox as minor modifications of one great fundamental unity.
Moreover, the investigations of the last three-quarters of a century
have proved, they tell us, that similar inquiries, carried out through
all the different kinds of animals which are met with in nature, will
lead us, not in one straight series, but by many roads, step by step,
gradation by gradation, from man, at the summit, to specks of animated
jelly at the bottom of the series. So that the idea of Leibnitz, and of
Bonnet, that animals form a great scale of being, in which there are a
series of gradations from the most complicated form to the lowest and
simplest; that idea, though not exactly in the form in which it was
propounded by those philosophers, turns out to be substantially correct.
More than this, when biologists pursue their investigations into the
vegetable world, they find that they can, in the same way, follow out
the structure of the plant, from the most gigantic and complicated trees
down through a similar series of gradations, until they arrive at specks
of animated jelly, which they are puzzled to distinguish from those
specks which they reached by the animal road.
Thus, biologists have arrived at the conclusion that a fundamental
uniformity of structure pervades the animal and vegetable worlds, and
that plants and animals differ from one another simply as diverse
modifications of the same great general plan.
Again, they tell us the same story in regard to the study of function.
They admit the large and important interval which, at the present time,
separates the manifestations of the mental faculties observable in the
higher forms of mankind, and even in the lower forms, such as we know
them, from those exhibited by other animals; but, at the same time, they
tell us that the foundations, or rudiments, of almost all the faculties
of man are to be met with in the lower animals; that there is a unity of
mental faculty as well as of bodily structure, and that, here also, the
difference is a difference of degree and not of kind. I said "almost
all," for a reason. Among the many distinctions which have been drawn
between the lower creatures and ourselves, there is one which is hardly
ever insisted on,[4] but which may be very fitly spoken of in a place so
largely devoted to Art as that in which we are assembled. It is this,
that while, among various kinds of animals, it is possible to discover
traces of all the other faculties of man, especially the faculty of
mimicry, yet that particular form of mimicry which shows itself in the
imitation of form, either by modelling or by drawing, is not to be met
with. As far as I know, there is no sculpture or modelling, and
decidedly no painting or drawing, of animal origin, I mention the fact,
in order that such comfort may be derived therefrom as artists may feel
inclined to take.
If what the biologists tell us is true, it will be needful to get rid of
our erroneous conceptions of man, and of his place in nature, and to
substitute right ones for them. But it is impossible to form any
judgment as to whether the biologists are right or wrong, unless we are
able to appreciate the nature of the arguments which they have to offer.
One would almost think this to be a self-evident proposition. I wonder
what a scholar would say to the man who should undertake to criticise a
difficult passage in a Greek play, but who obviously had not acquainted
himself with the rudiments of Greek grammar. And yet, before giving
positive opinions about these high questions of Biology, people not only
do not seem to think it necessary to be acquainted with the grammar of
the subject, but they have not even mastered the alphabet. You find
criticism and denunciation showered about by persons, who, not only have
not attempted to go through the discipline necessary to enable them to
be judges, but who have not even reached that stage of emergence from
ignorance in which the knowledge that such a discipline is necessary
dawns upon the mind. I have had to watch with some attention--in fact I
have been favoured with a good deal of it myself--the sort of criticism
with which biologists and biological teachings are visited. I am told
every now and then that there is a "brilliant article"[5] in so-and-so,
in which we are all demolished. I used to read these things once, but I
am getting old now, and I have ceased to attend very much to this cry of
"wolf." When one does read any of these productions, what one finds
generally, on the face of it, is that the brilliant critic is devoid of
even the elements of biological knowledge, and that his brilliancy is
like the light given out by the crackling of thorns under a pot of which
Solomon speaks. So far as I recollect, Solomon makes use of the image
for purposes of comparison; but I will not proceed further into that
matter.
Two things must be obvious: in the first place, that every man who has
the interests of truth at heart must earnestly desire that every
well-founded and just criticism that can be made should be made; but
that, in the second place, it is essential to anybody's being able to
benefit by criticism, that the critic should know what he is talking
about, and be in a position to form a mental image of the facts
symbolised by the words he uses. If not, it is as obvious in the case of
a biological argument, as it is in that of a historical or philological
discussion, that such criticism is a mere waste of time on the part of
its author, and wholly undeserving of attention on the part of those who
are criticised. Take it then as an illustration of the importance of
biological study, that thereby alone are men able to form something like
a rational conception of what constitutes valuable criticism of the
teachings of biologists.[6]
Next, I may mention another bearing of biological knowledge--a more
practical one in the ordinary sense of the word. Consider the theory of
infectious disease. Surely that is of interest to all of us. Now the
theory of infectious disease is rapidly being elucidated by biological
study. It is possible to produce, from among the lower animals, examples
of devastating diseases which spread in the same manner as our
infectious disorders, and which are certainly and unmistakably caused by
living organisms. This fact renders it possible, at any rate, that that
doctrine of the causation of infectious disease which is known under the
name of "the germ theory" may be well-founded; and, if so, it must needs
lead to the most important practical measures in dealing with those
terrible visitations. It may be well that the general, as well as the
professional, public should have a sufficient knowledge of biological
truths to be able to take a rational interest in the discussion of such
problems, and to see, what I think they may hope to see, that, to those
who possess a sufficient elementary knowledge of Biology, they are not
all quite open questions.
Let me mention another important practical illustration of the value of
biological study. Within the last forty years the theory of agriculture
has been revolutionised. The researches of Liebig, and those of our own
Lawes and Gilbert, have had a bearing upon that branch of industry the
importance of which cannot be overestimated; but the whole of these new
views have grown out of the better explanation of certain processes
which go on in plants; and which, of course, form a part of the
subject-matter of Biology.
I might go on multiplying these examples, but I see that the clock won't
wait for me, and I must therefore pass to the third question to which I
referred: Granted that Biology is something worth studying, what is the
best way of studying it? Here I must point out that, since Biology is a
physical science, the method of studying it must needs be analogous to
that which is followed in the other physical sciences. It has now long
been recognised that, if a man wishes to be a chemist, it is not only
necessary that he should read chemical books and attend chemical
lectures, but that he should actually perform the fundamental
experiments in the laboratory for himself, and thus learn exactly what
the words which he finds in his books and hears from his teachers, mean.
If he does not do so, he may read till the crack of doom, but he will
never know much about chemistry. That is what every chemist will tell
you, and the physicist will do the same for his branch of science. The
great changes and improvements in physical and chemical scientific
education, which have taken place of late, have all resulted from the
combination of practical teaching with the reading of books and with the
hearing of lectures. The same thing is true in Biology. Nobody will ever
know anything about Biology except in a dilettante "paper-philosopher"
way, who contents himself with reading books on botany, zoology, and the
like; and the reason of this is simple and easy to understand. It is
that all language is merely symbolical of the things of which it treats;
the more complicated the things, the more bare is the symbol, and the
more its verbal definition requires to be supplemented by the
information derived directly from the handling, and the seeing, and the
touching of the thing symbolised:--that is really what is at the bottom
of the whole matter. It is plain common sense, as all truth, in the long
run, is only common sense clarified. If you want a man to be a tea
merchant, you don't tell him to read books about China or about tea, but
you put him into a tea-merchant's office where he has the handling, the
smelling, and the tasting of tea. Without the sort of knowledge which
can be gained only in this practical way, his exploits as a tea merchant
will soon come to a bankrupt termination. The "paper-philosophers" are
under the delusion that physical science can be mastered as literary
accomplishments are acquired, but unfortunately it is not so. You may
read any quantity of books, and you may be almost as ignorant as you
were at starting, if you don't have, at the back of your minds, the
change for words in definite images which can only be acquired through
the operation of your observing faculties on the phenomena of nature.
It may be said:--"That is all very well, but you told us just now that
there are probably something like a quarter of a million different kinds
of living and extinct animals and plants, and a human life could not
suffice for the examination of one-fiftieth part of all these." That is
true, but then comes the great convenience of the way things are
arranged; which is, that although there are these immense numbers of
different kinds of living things in existence, yet they are built up,
after all, upon marvellously few plans.
There are certainly more than 100,000 species of insects, and yet
anybody who knows one insect--if a properly chosen one--will be able to
have a very fair conception of the structure of the whole. I do not mean
to say he will know that structure thoroughly, or as well as it is
desirable he should know it; but he will have enough real knowledge to
enable him to understand what he reads, to have genuine images in his
mind of those structures which become so variously modified in all the
forms of insects he has not seen. In fact, there are such things as
types of form among animals and vegetables, and for the purpose of
getting a definite knowledge of what constitutes the leading
modifications of animal and plant life, it is not needful to examine
more than a comparatively small number of animals and plants.
Let me tell you what we do in the biological laboratory which is lodged
in a building adjacent to this. There I lecture to a class of students
daily for about four-and-a-half months, and my class have, of course,
their text-books; but the essential part of the whole teaching, and that
which I regard as really the most important part of it, is a laboratory
for practical work, which is simply a room with all the appliances
needed for ordinary dissection. We have tables properly arranged in
regard to light, microscopes, and dissecting instruments, and we work
through the structure of a certain number of animals and plants. As, for
example, among the plants, we take a yeast plant, a _Protococcus_, a
common mould, a _Chara_, a fern, and some flowering plant; among animals
we examine such things as an _Amoeba_, a _Vorticella_, and a
fresh-water polype. We dissect a star-fish, an earth-worm, a snail, a
squid, and a fresh-water mussel. We examine a lobster and a cray-fish,
and a black beetle. We go on to a common skate, a cod-fish, a frog, a
tortoise, a pigeon, and a rabbit, and that takes us about all the time
we have to give. The purpose of this course is not to make skilled
dissectors, but to give every student a clear and definite conception,
by means of sense-images, of the characteristic structure of each of the
leading modifications of the animal kingdom; and that is perfectly
possible, by going no further than the length of that list of forms
which I have enumerated. If a man knows the structure of the animals I
have mentioned, he has a clear and exact, however limited, apprehension
of the essential features of the organisation of all those great
divisions of the animal and vegetable kingdoms to which the forms I have
mentioned severally belong. And it then becomes possible for him to read
with profit; because every time he meets with the name of a structure,
he has a definite image in his mind of what the name means in the
particular creature he is reading about, and therefore the reading is
not mere reading. It is not mere repetition of words; but every term
employed in the description, we will say, of a horse, or of an elephant,
will call up the image of the things he had seen in the rabbit, and he
is able to form a distinct conception of that which he has not seen, as
a modification of that which he has seen.
I find this system to yield excellent results; and I have no hesitation
whatever in saying, that any one who has gone through such a course,
attentively, is in a better position to form a conception of the great
truths of Biology, especially of morphology (which is what we chiefly
deal with), than if he had merely read all the books on that topic put
together.
The connection of this discourse with the Loan Collection of Scientific
Apparatus arises out of the exhibition in that collection of certain
aids to our laboratory work. Such of you as have visited that very
interesting collection may have noticed a series of diagrams and of
preparations illustrating the structure of a frog. Those diagrams and
preparations have been made for the use of the students in the
biological laboratory. Similar diagrams and preparations illustrating
the structure of all the other forms of life we examine, are either made
or in course of preparation. Thus the student has before him, first, a
picture of the structure he ought to see; secondly, the structure itself
worked out; and if with these aids, and such needful explanations and
practical hints as a demonstrator can supply, he cannot make out the
facts for himself in the materials supplied to him, he had better take
to some other pursuit than that of biological science.
I should have been glad to have said a few words about the use of
museums in the study of Biology, but I see that my time is becoming
short, and I have yet another question to answer. Nevertheless I must,
at the risk of wearying you, say a word or two upon the important
subject of museums. Without doubt there are no helps to the study of
Biology, or rather to some branches of it, which are, or may be, more
important than natural history museums; but, in order to take this place
in regard to Biology, they must be museums of the future. The museums of
the present do not, by any means, do so much for us as they might do. I
do not wish to particularise, but I dare say many of you, seeking
knowledge, or in the laudable desire to employ a holiday usefully, have
visited some great natural history museum. You have walked through a
quarter of a mile of animals, more or less well stuffed, with their long
names written out underneath them; and, unless your experience is very
different from that of most people, the upshot of it all is that you
leave that splendid pile with sore feet, a bad headache, and a general
idea that the animal kingdom is a "mighty maze without a plan." I do not
think that a museum which brings about this result does all that may be
reasonably expected from such an institution. What is needed in a
collection of natural history is that it should be made as accessible
and as useful as possible, on the one hand to the general public, and on
the other to scientific workers. That need is not met by constructing a
sort of happy hunting-ground of miles of glass cases; and, under the
pretence of exhibiting everything, putting the maximum amount of
obstacle in the way of those who wish properly to see anything.
What the public want is easy and unhindered access to such a collection
as they can understand and appreciate; and what the men of science want
is similar access to the materials of science. To this end the vast mass
of objects of natural history should be divided into two parts--one open
to the public, the other to men of science, every day. The former
division should exemplify all the more important and interesting forms
of life. Explanatory tablets should be attached to them, and catalogues
containing clearly-written popular expositions of the general
significance of the objects exhibited should be provided. The latter
should contain, packed into a comparatively small space, in rooms
adapted for working purposes, the objects of purely scientific interest.
For example, we will say I am an ornithologist. I go to examine a
collection of birds. It is a positive nuisance to have them stuffed. It
is not only sheer waste, but I have to reckon with the ideas of the
bird-stuffer, while, if I have the skin and nobody has interfered with
it, I can form my own judgment as to what the bird was like. For
ornithological purposes, what is needed is not glass cases full of
stuffed birds on perches, but convenient drawers into each of which a
great quantity of skins will go. They occupy no great space and do not
require any expenditure beyond their original cost. But for the
edification of the public, who want to learn indeed, but do not seek for
minute and technical knowledge, the case is different. What one of the
general public walking into a collection of birds desires to see is not
all the birds that can be got together. He does not want to compare a
hundred species of the sparrow tribe side by side; but he wishes to know
what a bird is, and what are the great modifications of bird structure,
and to be able to get at that knowledge easily. What will best serve his
purpose is a comparatively small number of birds carefully selected, and
artistically, as well as accurately, set up; with their different ages,
their nests, their young, their eggs, and their skeletons side by side;
and in accordance with the admirable plan which is pursued in this
museum, a tablet, telling the spectator in legible characters what they
are and what they mean. For the instruction and recreation of the public
such a typical collection would be of far greater value than any
many-acred imitation of Noah's ark.
Lastly comes the question as to when biological study may best be
pursued. I do not see any valid reason why it should not be made, to a
certain extent, a part of ordinary school training. I have long
advocated this view, and I am perfectly certain that it can be carried
out with ease, and not only with ease, but with very considerable profit
to those who are taught; but then such instruction must be adapted to
the minds and needs of the scholars. They used to have a very odd way of
teaching the classical languages when I was a boy. The first task set
you was to learn the rules of the Latin grammar in the Latin
language--that being the language you were going to learn! I thought
then that this was an odd way of learning a language, but did not
venture to rebel against the judgment of my superiors. Now, perhaps, I
am not so modest as I was then, and I allow myself to think that it was
a very absurd fashion. But it would be no less absurd, if we were to set
about teaching Biology by putting into the hands of boys a series of
definitions of the classes and orders of the animal kingdom, and making
them repeat them by heart. That is so very favourite a method of
teaching, that I sometimes fancy the spirit of the old classical system
has entered into the new scientific system, in which case I would much
rather that any pretence at scientific teaching were abolished
altogether. What really has to be done is to get into the young mind
some notion of what animal and vegetable life is. In this matter, you
have to consider practical convenience as well as other things. There
are difficulties in the way of a lot of boys making messes with slugs
and snails; it might not work in practice. But there is a very
convenient and handy animal which everybody has at hand, and that is
himself; and it is a very easy and simple matter to obtain common
plants. Hence the general truths of anatomy and physiology can be taught
to young people in a very real fashion by dealing with the broad facts
of human structure. Such viscera as they cannot very well examine in
themselves, such as hearts, lungs, and livers, may be obtained from the
nearest butcher's shop. In respect to teaching something about the
biology of plants, there is no practical difficulty, because almost any
of the common plants will do, and plants do not make a mess--at least
they do not make an unpleasant mess; so that, in my judgment, the best
form of Biology for teaching to very young people is elementary human
physiology on the one hand, and the elements of botany on the other;
beyond that I do not think it will be feasible to advance for some time
to come. But then I see no reason why, in secondary schools, and in the
Science Classes which are under the control of the Science and Art
Department--and which I may say, in passing, have, in my judgment, done
so very much for the diffusion of a knowledge of science over the
country--we should not hope to see instruction in the elements of
Biology carried out, not perhaps to the same extent, but still upon
somewhat the same principle as here. There is no difficulty, when you
have to deal with students of the ages of 15 or 16, in practising a
little dissection and in getting a notion of, at any rate, the four or
five great modifications of the animal form; and the like is true in
regard to the higher anatomy of plants.
While, lastly, to all those who are studying biological science with a
view to their own edification merely, or with the intention of becoming
zoologists or botanists; to all those who intend to pursue
physiology--and especially to those who propose to employ the working
years of their lives in the practice of medicine--I say that there is no
training so fitted, or which may be of such important service to them,
as the discipline in practical biological work which I have sketched out
as being pursued in the laboratory hard by.
* * * * *
I may add that, beyond all these different classes of persons who may
profit by the study of Biology, there is yet one other. I remember, a
number of years ago, that a gentleman who was a vehement opponent of Mr.
Darwin's views and had written some terrible articles against them,
applied to me to know what was the best way in which he could acquaint
himself with the strongest arguments in favour of evolution. I wrote
back, in all good faith and simplicity, recommending him to go through a
course of comparative anatomy and physiology, and then to study
development. I am sorry to say he was very much displeased, as people
often are with good advice. Notwithstanding this discouraging result, I
venture, as a parting word, to repeat the suggestion, and to say to all
the more or less acute lay and clerical "paper-philosophers"[7] who
venture into the regions of biological controversy--Get a little sound,
thorough, practical, elementary instruction in biology.
[1] See the distinction between the "sciences physiques" and the
"sciences physiologiques" in the "Anatomic Générale," 1801.
[2] "Hydrogeologie," an. x. (1801).
[3] "The term _Biology_, which means exactly what we wish to
express, _the Science of Life_, has often been used, and has of
late become not uncommon, among good writers."--Whewell,
"Philosophy of the Inductive Sciences," vol. i. p. 544 (edition
of 1847).
[4] I think that my friend Professor Allman was the first to draw
attention to it.
[5] Galileo was troubled by a sort of people whom he called "paper
philosophers," because they fancied that the true reading of
nature was to be detected by the collation of texts. The race is
not extinct, but, as of old, brings forth its "winds of
doctrine" by which the weathercock heads among us are much
exercised.
[6] Some critics do not even take the trouble to read. I have
recently been adjured with much solemnity, to state publicly why
I have "changed my opinion" as to the value of the
palæontological evidence of the occurrence of evolution.
To this my reply is, Why should I, when that statement was made
seven years ago? An address delivered from the Presidential
Chair of the Geological Society, in 1870, may be said to be a
public document, inasmuch as it not only appeared in the
_Journal_ of that learned body, but was re-published, in 1873,
in a volume of "Critiques and Addresses," to which my name is
attached. Therein will be found a pretty full statement of my
reasons for enunciating two propositions: (1) that "when we turn
to the higher _Vertebrata_, the results of recent
investigations, however we may sift and criticise them, seem to
me to leave a clear balance in favour of the evolution of living
forms one from another;" and (2) that the case of the horse is
one which "will stand rigorous criticism."
Thus I do not see clearly in what way I can be said to have
changed my opinion, except in the way of intensifying it, when
in consequence of the accumulation of similar evidence since
1870, I recently spoke of the denial of evolution as not worth
serious consideration.
[7] Writers of this stamp are fond of talking about the Baconian
method. I beg them therefore to lay to heart these two weighty
sayings of the herald of Modern Science:--
"Syllogismus ex propositionibus constat, propositiones ex
verbis, verba notionum tesseræ sunt. Itaque si notiones ipsæ
(_id quod basis rei est_) confusæ sint et temere a rebus
abstractæ, nihil in iis quæ superstruuntur est
firmitudinis."--"Novum Organon," ii. 14.
"Huic autem vanitati nonnulli ex modernis summa levitate ita
indulserunt, ut in primo capitulo Geneseos et in libro Job
et aliis scripturis sacris, philosophiam naturalem fundare
conati sint; _inter vivos quærentes mortua_."--_Ibid._, 65.
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