IX

A CRITICAL EXAMINATION OF THE POSITION OF MR. DARWIN'S WORK, "ON THE

ORIGIN OF SPECIES," IN RELATION TO THE COMPLETE THEORY OF THE CAUSES

OF THE PHENOMENA OF ORGANIC NATURE.

In the preceding lectures I have endeavoured to give you an account of

those facts, and of those reasonings from facts, which form the data

upon which all theories regarding the causes of the phenomena of organic

nature must be based. And, although I have had frequent occasion to

quote Mr. Darwin--as all persons hereafter, in speaking upon these

subjects, will have occasion to quote his famous book on the "Origin of

Species,"--you must yet remember that, wherever I have quoted him, it

has not been upon theoretical points, or for statements in any way

connected with his particular speculations, but on matters of fact,

brought forward by himself, or collected by himself, and which appear

incidentally in his book. If a man _will_ make a book, professing to

discuss a single question, an encyclopædia, I cannot help it.

Now, having had an opportunity of considering in this sort of way the

different statements bearing upon all theories whatsoever, I have to lay

before you, as fairly as I can, what is Mr. Darwin's view of the matter

and what position his theories hold, when judged by the principles which

I have previously laid down, as deciding our judgments upon all theories

and hypotheses.

I have already stated to you that the inquiry respecting the causes of

the phenomena of organic nature resolves itself into two problems--the

first being the question of the origination of living or organic

beings; and the second being the totally distinct problem of the

modification and perpetuation of organic beings when they have already

come into existence. The first question Mr. Darwin does not touch; he

does not deal with it at all; but he says:--"Given the origin of organic

matter--supposing its creation to have already taken place, my object is

to show in consequence of what laws and what demonstrable properties of

organic matter, and of its environments, such states of organic nature

as those with which we are acquainted must have come about." This, you

will observe, is a perfectly legitimate proposition; every person has a

right to define the limits of the inquiry which he sets before himself;

and yet it is a most singular thing that in all the multifarious, and,

not unfrequently, ignorant attacks which have been made upon the "Origin

of Species," there is nothing which has been more speciously criticised

than this particular limitation. If people have nothing else to urge

against the book, they say--"Well, after all, you see Mr. Darwin's

explanation of the 'Origin of Species' is not good for much, because, in

the long run, he admits that he does not know how organic matter began

to exist. But if you admit any special creation for the first particle

of organic matter you may just as well admit it for all the rest; five

hundred or five thousand distinct creations are just as intelligible,

and just as little difficult to understand, as one." The answer to these

cavils is two-fold. In the first place, all human inquiry must stop

somewhere; all our knowledge and all our investigation cannot take us

beyond the limits set by the finite and restricted character of our

faculties, or destroy the endless unknown, which accompanies, like its

shadow, the endless procession of phenomena. So far as I can venture to

offer an opinion on such a matter, the purpose of our being in

existence, the highest object that human beings can set before

themselves, is not the pursuit of any such chimera as the annihilation

of the unknown; but it is simply the unwearied endeavour to remove its

boundaries a little further from our little sphere of action.

I wonder if any historian would for a moment admit the objection, that

it is preposterous to trouble ourselves about the history of the Roman

Empire, because we do not know anything positive about the origin and

first building of the city of Rome! Would it be a fair objection to

urge, respecting the sublime discoveries of a Newton, or a Kepler, those

great philosophers, whose discoveries have been of the profoundest

benefit and service to all men,--to say to them--"After all that you

have told us as to how the planets revolve, and how they are maintained

in their orbits, you cannot tell us what is the cause of the origin of

the sun, moon, and stars. So what is the use of what you have done?" Yet

these objections would not be one whit more preposterous than the

objections which have been made to the "Origin of Species." Mr. Darwin,

then, had a perfect right to limit his inquiry as he pleased, and the

only question for us--the inquiry being so limited--is to ascertain

whether the method of his inquiry is sound or unsound; whether he has

obeyed the canons which must guide and govern all investigation, or

whether he has broken them; and it was because our inquiry this evening

is essentially limited to that question, that I spent a good deal of

time in a former lecture (which, perhaps some of you thought might have

been better employed) in endeavouring to illustrate the method and

nature of scientific inquiry in general. We shall now have to put in

practice the principles that I then laid down.

I stated to you in substance, if not in words, that wherever there are

complex masses of phenomena to be inquired into, whether they be

phenomena of the affairs of daily life, or whether they belong to the

more abstruse and difficult problems laid before the philosopher, our

course of proceeding in unravelling that complex chain of phenomena with

a view to get at its cause, is always the same; in all cases we must

invent an hypothesis; we must place before ourselves some more or less

likely supposition respecting that cause; and then, having assumed an

hypothesis, having supposed a cause for the phenomena in question, we

must endeavour, on the one hand, to demonstrate our hypothesis, or, on

the other, to upset and reject it altogether, by testing it in three

ways. We must, in the first place, be prepared to prove that the

supposed causes of the phenomena exist in nature; that they are what

the logicians call _vera causæ_--true causes;--in the next place, we

should be prepared to show that the assumed causes of the phenomena are

competent to produce such phenomena as those which we wish to explain by

them; and in the last place, we ought to be able to show that no other

known causes are competent to produce these phenomena. If we can succeed

in satisfying these three conditions we shall have demonstrated our

hypothesis; or rather I ought to say, we shall have proved it as far as

certainty is possible for us; for, after all, there is no one of our

surest convictions which may not be upset, or at any rate modified by a

further accession of knowledge. It was because it satisfied these

conditions that we accepted the hypothesis as to the disappearance of

the tea-pot and spoons in the case I supposed in a previous lecture; we

found that our hypothesis on that subject was tenable and valid, because

the supposed cause existed in nature, because it was competent to

account for the phenomena, and because no other known cause was

competent to account for them; and it is upon similar grounds that any

hypothesis you choose to name is accepted in science as tenable and

valid.

What is Mr. Darwin's hypothesis? As I apprehend it--for I have put it

into a shape more convenient for common purposes than I could find

_verbatim_ in his book--as I apprehend it, I say, it is, that all the

phenomena of organic nature, past and present, result from, or are

caused by, the inter-action of those properties of organic matter, which

we have called ATAVISM and VARIABILITY, with the CONDITIONS OF

EXISTENCE; or, in other words,--given the existence of organic matter,

its tendency to transmit its properties, and its tendency occasionally

to vary; and, lastly, given the conditions of existence by which organic

matter is surrounded--that these put together are the causes of the

Present and of the Past conditions of ORGANIC NATURE.

Such is the hypothesis as I understand it. Now let us see how it will

stand the various tests which I laid down just now. In the first place,

do these supposed causes of the phenomena exist in nature? Is it the

fact that in nature these properties of organic matter--atavism and

variability--and those phenomena which we have called the conditions of

existence,--is it true that they exist? Well, of course, if they do not

exist, all that I have told you in the last three or four lectures must

be incorrect, because I have been attempting to prove that they do

exist, and I take it that there is abundant evidence that they do exist;

so far, therefore, the hypothesis does not break down.

But in the next place comes a much more difficult inquiry:--Are the

causes indicated competent to give rise to the phenomena of organic

nature? I suspect that this is indubitable to a certain extent. It is

demonstrable, I think, as I have endeavoured to show you, that they are

perfectly competent to give rise to all the phenomena which are

exhibited by RACES in nature. Furthermore, I believe that they are quite

competent to account for all that we may call purely structural

phenomena which are exhibited by SPECIES in nature. On that point also I

have already enlarged somewhat. Again, I think that the causes assumed

are competent to account for most of the physiological characteristics

of species, and I not only think that they are competent to account for

them, but I think that they account for many things which otherwise

remain wholly unaccountable and inexplicable, and I may say

incomprehensible. For a full exposition of the grounds on which this

conviction is based, I must refer you to Mr. Darwin's work; all that I

can do now is to illustrate what I have said by two or three cases taken

almost at random.

I drew your attention, on a previous evening, to the facts which are

embodied in our systems of Classification, which are the results of the

examination and comparison of the different members of the animal

kingdom one with another. I mentioned that the whole of the animal

kingdom is divisible into five sub-kingdoms; that each of these

sub-kingdoms is again divisible into provinces; that each province may

be divided into classes, and the classes into the successively smaller

groups, orders, families, genera, and species.

Now, in each of these groups, the resemblance in structure among the

members of the group is closer in proportion as the group is smaller.

Thus, a man and a worm are members of the animal kingdom in virtue of

certain apparently slight though really fundamental resemblances which

they present. But a man and a fish are members of the same Sub-kingdom

_Vertebrata_, because they are much more like one another than either of

them is to a worm, or a snail, or any member of the other sub-kingdoms.

For similar reasons men and horses are arranged as members of the same

Class, _Mammalia_; men and apes as members of the same Order,

_Primates_; and if there were any animals more like men than they were

like any of the apes, and yet different from men in important and

constant particulars of their organization, we should rank them as

members of the same Family, or of the same Genus, but as of distinct

Species.

That it is possible to arrange all the varied forms of animals into

groups, having this sort of singular subordination one to the other, is

a very remarkable circumstance; but, as Mr. Darwin remarks, this is a

result which is quite to be expected, if the principles which he lays

down be correct. Take the case of the races which are known to be

produced by the operation of atavism and variability, and the conditions

of existence which check and modify these tendencies. Take the case of

the pigeons that I brought before you: there it was shown that they

might be all classed as belonging to some one of five principal

divisions, and that within these divisions other subordinate groups

might be formed. The members of these groups are related to one another

in just the same way as the genera of a family, and the groups

themselves as the families of an order, or the orders of a class; while

all have the same sort of structural relations with the wild

Rock-pigeon, as the members of any great natural group have with a real

or imaginary typical form. Now, we know that all varieties of pigeons of

every kind have arisen by a process of selective breeding from a common

stock, the Rock-pigeon; hence, you see, that if all species of animals

have proceeded from some common stock, the general character of their

structural relations, and of our systems of classification, which

express those relations, would be just what we find them to be. In

other words, the hypothetical cause is, so far, competent to produce

effects similar to those of the real cause.

Take, again, another set of very remarkable facts,--the existence of

what are called rudimentary organs, organs for which we can find no

obvious use, in the particular animal economy in which they are found,

and yet which are there.

Such are the splint-like bones in the leg of the horse, which I here

show you, and which correspond with bones which belong to certain toes

and fingers in the human hand and foot. In the horse you see they are

quite rudimentary, and bear neither toes nor fingers; so that the horse

has only one "finger" in his fore-foot and one "toe" in his hind-foot.

But it is a very curious thing that the animals closely allied to the

horse show more toes than he; as the rhinoceros, for instance: he has

these extra toes well formed, and anatomical facts show very clearly

that he is very closely related to the horse indeed. So we may say that

animals, in an anatomical sense nearly related to the horse, have those

parts which are rudimentary in him, fully developed.

Again, the sheep and the cow have no cutting-teeth, but only a hard pad

in the upper jaw. That is the common characteristic of ruminants in

general. But the calf has in its upper jaw some rudiments of teeth which

never are developed, and never play the part of teeth at all. Well, if

you go back in time, you find some of the older, now extinct, allies of

the ruminants have well-developed teeth in their upper jaws; and at the

present day the pig (which is in structure closely connected with

ruminants) has well-developed teeth in its upper jaw; so that here is

another instance of organs well developed and very useful, in one

animal, represented by rudimentary organs, for which we can discover no

purpose whatsoever, in another closely allied animal. The whalebone

whale, again, has horny "whalebone" plates in its mouth, and no teeth;

but the young foetal whale, before it is born, has teeth in its jaws;

they, however, are never used, and they never come to anything. But

other members of the group to which the whale belongs have

well-developed teeth in both jaws.

Upon any hypothesis of special creation, facts of this kind appear to me

to be entirely unaccountable and inexplicable, but they cease to be so

if you accept Mr. Darwin's hypothesis, and see reason for believing that

the whalebone whale and the whale with teeth in its mouth both sprang

from a whale that had teeth, and that the teeth of the foetal whale

are merely remnants--recollections, if we may so say--of the extinct

whale. So in the case of the horse and the rhinoceros: suppose that both

have descended by modification from some earlier form which had the

normal number of toes, and the persistence of the rudimentary bones

which no longer support toes in the horse becomes comprehensible.

In the language that we speak in England, and in the language of the

Greeks, there are identical verbal roots, or elements entering into the

composition of words. That fact remains unintelligible so long as we

suppose English and Greek to be independently created tongues; but when

it is shown that both languages are descended from one original, the

Sanscrit, we give an explanation of that resemblance. In the same way

the existence of identical structural roots, if I may so term them,

entering into the composition of widely different animals, is striking

evidence in favour of the descent of those animals from a common

original.

To turn to another kind of illustration:--If you regard the whole series

of stratified rocks--that enormous thickness of sixty or seventy

thousand feet that I have mentioned before, constituting the only record

we have of a most prodigious lapse of time, that time being, in all

probability, but a fraction of that of which we have no record;--if you

observe in these successive strata of rocks successive groups of animals

arising and dying out, a constant succession, giving you the same kind

of impression, as you travel from one group of strata to another, as you

would have in travelling from one country to another;--when you find

this constant succession of forms, their traces obliterated except to

the man of science,--when you look at this wonderful history, and ask

what it means, it is only a paltering with words if you are offered the

reply,--"They were so created."

But if, on the other hand, you look on all forms of organized beings as

the results of the gradual modification of a primitive type, the facts

receive a meaning, and you see that these older conditions are the

necessary predecessors of the present. Viewed in this light the facts of

palæontology receive a meaning--upon any other hypothesis, I am unable

to see, in the slightest degree, what knowledge or signification we are

to draw out of them. Again, note as bearing upon the same point, the

singular likeness which obtains between the successive Faunæ and Floræ,

whose remains are preserved on the rocks: you never find any great and

enormous difference between the immediately successive Faunæ and Floræ,

unless you have reason to believe there has also been a great lapse of

time or a great change of conditions. The animals, for instance, of the

newest tertiary rocks, in any part of the world, are always, and without

exception, found to be closely allied with those which now live in that

part of the world. For example, in Europe, Asia, and Africa, the large

mammals are at present rhinoceri, hippopotami, elephants, lions, tigers,

oxen, horses, &c.; and if you examine the newest tertiary deposits,

which contain the animals and plants which immediately preceded those

which now exist in the same country, you do not find gigantic specimens

of ant-eaters and kangaroos, but you find rhinoceroses, elephants,

lions, tigers, &c.,--of different species to those now living,--but

still their close allies. If you turn to South America, where, at the

present day, we have great sloths and armadilloes and creatures of that

kind, what do you find in the newest tertiaries? You find the great

sloth-like creature, the _Megatherium_, and the great armadillo, the

_Glyptodon_, and so on. And if you go to Australia you find the same law

holds good, namely, that that condition of organic nature which has

preceded the one which now exists, presents differences perhaps of

species, and of genera, but that the great types of organic structure

are the same as those which now flourish.

What meaning has this fact upon any other hypothesis or supposition than

one of successive modification? But if the population of the world, in

any age, is the result of the gradual modification of the forms which

peopled it in the preceding age,--if that has been the case, it is

intelligible enough; because we may expect that the creature that

results from the modification of an elephantine mammal shall be

something like an elephant, and the creature which is produced by the

modification of an armadillo-like mammal shall be like an armadillo.

Upon that supposition, I say, the facts are intelligible; upon any

other, that I am aware of, they are not.

So far, the facts of palæontology are consistent with almost any form of

the doctrine of progressive modification; they would not be absolutely

inconsistent with the wild speculations of De Maillet, or with the less

objectionable hypothesis of Lamarck. But Mr. Darwin's views have one

peculiar merit; and that is, that they are perfectly consistent with an

array of facts which are utterly inconsistent with and fatal to, any

other hypothesis of progressive modification which has yet been

advanced. It is one remarkable peculiarity of Mr. Darwin's hypothesis

that it involves no necessary progression or incessant modification, and

that it is perfectly consistent with the persistence for any length of

time of a given primitive stock, contemporaneously with its

modifications. To return to the case of the domestic breeds of pigeons,

for example; you have the Dove-cot pigeon, which closely resembles the

Rock-pigeon, from which they all started, existing at the same time with

the others. And if species are developed in the same way in nature, a

primitive stock and its modifications may, occasionally, all find the

conditions fitted for their existence; and though they come into

competition, to a certain extent, with one another, the derivative

species may not necessarily extirpate the primitive one, or _vice

versâ_.

Now palæontology shows us many facts which are perfectly harmonious with

these observed effects of the process by which Mr. Darwin supposes

species to have originated, but which appear to me to be totally

inconsistent with any other hypothesis which has been proposed. There

are some groups of animals and plants, in the fossil world, which have

been said to belong to "persistent types," because they have persisted,

with very little change indeed, through a very great range of time,

while everything about them has changed largely. There are families of

fishes whose type of construction has persisted all the way from the

carboniferous rock right up to the cretaceous; and others which have

lasted through almost the whole range of the secondary rocks, and from

the lias to the older tertiaries. It is something stupendous this--to

consider a genus lasting without essential modifications through all

this enormous lapse of time while almost everything else was changed and

modified.

Thus I have no doubt that Mr. Darwin's hypothesis will be found

competent to explain the majority of the phenomena exhibited by species

in nature; but in an earlier lecture I spoke cautiously with respect to

its power of explaining all the physiological peculiarities of species.

There is, in fact, one set of these peculiarities which the theory of

selective modification, as it stands at present, is not wholly competent

to explain, and that is the group of phenomena which I mentioned to you

under the name of Hybridism, and which I explained to consist in the

sterility of the offspring of certain species when crossed one with

another. It matters not one whit whether this sterility is universal, or

whether it exists only in a single case. Every hypothesis is bound to

explain, or, at any rate, not be inconsistent with, the whole of the

facts which it professes to account for; and if there is a single one of

these facts which can be shown to be inconsistent with (I do not merely

mean inexplicable by, but contrary to,) the hypothesis, the hypothesis

falls to the ground,--it is worth nothing. One fact with which it is

positively inconsistent is worth as much, and as powerful in negativing

the hypothesis, as five hundred. If I am right in thus defining the

obligations of an hypothesis, Mr. Darwin, in order to place his views

beyond the reach of all possible assault, ought to be able to

demonstrate the possibility of developing from a particular stock by

selective breeding, two forms, which should either be unable to cross

one with another, or whose cross-bred offspring should be infertile with

one another.

For, you see, if you have not done that you have not strictly fulfilled

all the conditions of the problem; you have not shown that you can

produce, by the cause assumed, all the phenomena which you have in

nature. Here are the phenomena of Hybridism staring you in the face, and

you cannot say, "I can, by selective modification, produce these same

results." Now, it is admitted on all hands that, at present, so far as

experiments have gone, it has not been found possible to produce this

complete physiological divergence by selective breeding. I stated this

very clearly before, and I now refer to the point, because, if it could

be proved, not only that this _has_ not been done, but that it _cannot_

be done; if it could be demonstrated that it is impossible to breed

selectively, from any stock, a form which shall not breed with another,

produced from the same stock; and if we were shown that this must be the

necessary and inevitable result of all experiments, I hold that Mr.

Darwin's hypothesis would be utterly shattered.

But has this been done? or what is really the state of the case? It is

simply that, so far as we have gone yet with our breeding, we have not

produced from a common stock two breeds which are not more or less

fertile with one another.

I do not know that there is a single fact which would justify any one in

saying that any degree of sterility has been observed between breeds

absolutely known to have been produced by selective breeding from a

common stock. On the other hand, I do not know that there is a single

fact which can justify any one in asserting that such sterility cannot

be produced by proper experimentation. For my own part, I see every

reason to believe that it may, and will be so produced. For, as Mr.

Darwin has very properly urged, when we consider the phenomena of

sterility, we find they are most capricious; we do not know what it is

that the sterility depends on. There are some animals which will not

breed in captivity; whether it arises from the simple fact of their

being shut up and deprived of their liberty, or not, we do not know, but

they certainly will not breed. What an astounding thing this is, to find

one of the most important of all functions annihilated by mere

imprisonment!

So, again, there are cases known of animals which have been thought by

naturalists to be undoubted species, which have yielded perfectly

fertile hybrids; while there are other species which present what

everybody believes to be varieties[55] which are more or less infertile

with one another. There are other cases which are truly extraordinary;

there is one, for example, which has been carefully examined,--of two

kinds of sea-weed, of which the male element of the one, which we may

call A, fertilizes the female element of the other, B; while the male

element of B will not fertilize the female element of A; so that, while

the former experiment seems to show us that they are _varieties_, the

latter leads to the conviction that they are _species_.

When we see how capricious and uncertain this sterility is, how unknown

the conditions on which it depends, I say that we have no right to

affirm that those conditions will not be better understood by and by,

and we have no ground for supposing that we may not be able to

experiment so as to obtain that crucial result which I mentioned just

now. So that though Mr. Darwin's hypothesis does not completely

extricate us from this difficulty at present, we have not the least

right to say it will not do so.

There is a wide gulf between the thing you cannot explain and the thing

that upsets you altogether. There is hardly any hypothesis in this world

which has not some fact in connection with it which has not been

explained, but that is a very different affair to a fact that entirely

opposes your hypothesis; in this case all you can say is, that your

hypothesis is in the same position as a good many others.

Now, as to the third test, that there are no other causes competent to

explain the phenomena, I explained to you that one should be able to say

of an hypothesis, that no other known causes than those supposed by it

are competent to give rise to the phenomena. Here, I think, Mr. Darwin's

view is pretty strong. I really believe that the alternative is either

Darwinism or nothing, for I do not know of any rational conception or

theory of the organic universe which has any scientific position at all

beside Mr. Darwin's. I do not know of any proposition that has been put

before us with the intention of explaining the phenomena of organic

nature, which has in its favour a thousandth part of the evidence which

may be adduced in favour of Mr. Darwin's views. Whatever may be the

objections to his views, certainly all other theories are absolutely out

of court.

Take the Lamarckian hypothesis, for example. Lamarck was a great

naturalist, and to a certain extent went the right way to work; he

argued from what was undoubtedly a true cause of some of the phenomena

of organic nature. He said it is a matter of experience that an animal

may be modified more or less in consequence of its desires and

consequent actions. Thus, if a man exercise himself as a blacksmith, his

arms will become strong and muscular; such organic modification is a

result of this particular action and exercise. Lamarck thought that by a

very simple supposition based on this truth he could explain the origin

of the various animal species: he said, for example, that the

short-legged birds which live on fish, had been converted into the

long-legged waders by desiring to get the fish without wetting their

feathers, and so stretching their legs more and more through successive

generations. If Lamarck could have shown experimentally, that even races

of animals could be produced in this way, there might have been some

ground for his speculations. But he could show nothing of the kind, and

his hypothesis has pretty well dropped into oblivion, as it deserved to

do. I said in an earlier lecture that there are hypotheses and

hypotheses, and when people tell you that Mr. Darwin's strongly-based

hypothesis is nothing but a mere modification of Lamarck's, you will

know what to think of their capacity for forming a judgment on this

subject.

But you must recollect that when I say I think it is either Mr. Darwin's

hypothesis or nothing; that either we must take his view, or look upon

the whole of organic nature as an enigma, the meaning of which is wholly

hidden from us; you must understand that I mean that I accept it

provisionally, in exactly the same way as I accept any other hypothesis.

Men of science do not pledge themselves to creeds; they are bound by

articles of no sort; there is not a single belief that it is not a

bounden duty with them to hold with a light hand and to part with it,

cheerfully, the moment it is really proved to be contrary to any fact,

great or small. And if in course of time I see good reasons for such a

proceeding, I shall have no hesitation in coming before you, and

pointing out any change in my opinion without finding the slightest

occasion to blush for so doing. So I say that we accept this view as we

accept any other, so long as it will help us, and we feel bound to

retain it only so long as it will serve our great purpose--the

improvement of Man's estate and the widening of his knowledge. The

moment this, or any other conception, ceases to be useful for these

purposes, away with it to the four winds; we care not what becomes of

it!

But to say truth, although it has been my business to attend closely to

the controversies roused by the publication of Mr. Darwin's book, I

think that not one of the enormous mass of objections and obstacles

which have been raised is of any very great value, except that sterility

case which I brought before you just now. All the rest are

misunderstandings of some sort, arising either from prejudice, or want

of knowledge, or still more from want of patience and care in reading

the work.

For you must recollect that it is not a book to be read, with as much

ease, as its pleasant style may lead you to imagine. You spin through it

as if it were a novel the first time you read it, and think you know all

about it; the second time you read it you think you know rather less

about it; and the third time, you are amazed to find how little you have

really apprehended its vast scope and objects. I can positively say that

I never take it up without finding in it some new view, or light, or

suggestion that I have not noticed before. That is the best

characteristic of a thorough and profound book; and I believe this

feature of the "Origin of Species" explains why so many persons have

ventured to pass judgment and criticisms upon it which are by no means

worth the paper they are written on.

Before concluding these lectures there is one point to which I must

advert,--though, as Mr. Darwin has said nothing about man in his book,

it concerns myself rather than him;--for I have strongly maintained on

sundry occasions that if Mr. Darwin's views are sound, they apply as

much to man as to the lower mammals, seeing that it is perfectly

demonstrable that the structural differences which separate man from the

apes are not greater than those which separate some apes from others.

There cannot be the slightest doubt in the world that the argument which

applies to the improvement of the horse from an earlier stock, or of ape

from ape, applies to the improvement of man from some simpler and lower

stock than man. There is not a single faculty--functional or structural,

moral, intellectual, or instinctive,--there is no faculty whatever that

is not capable of improvement; there is no faculty whatsoever which does

not depend upon structure, and as structure tends to vary, it is capable

of being improved.

Well, I have taken a good deal of pains at various times to prove this,

and I have endeavoured to meet the objections of those who maintain,

that the structural differences between man and the lower animals are of

so vast a character and enormous extent, that even if Mr. Darwin's views

are correct, you cannot imagine this particular modification to take

place. It is, in fact, easy matter to prove that, so far as structure is

concerned, man differs to no greater extent from the animals which are

immediately below him than these do from other members of the same

order. Upon the other hand, there is no one who estimates more highly

than I do the dignity of human nature, and the width of the gulf in

intellectual and moral matters, which lies between man and the whole of

the lower creation.

But I find this very argument brought forward vehemently by some. "You

say that man has proceeded from a modification of some lower animal, and

you take pains to prove that the structural differences which are said

to exist in his brain do not exist at all, and you teach that all

functions, intellectual, moral, and others, are the expression or the

result, in the long run, of structures, and of the molecular forces

which they exert." It is quite true that I do so.

"Well, but," I am told at once, somewhat triumphantly, "you say in the

same breath that there is a great moral and intellectual chasm between

man and the lower animals. How is this possible when you declare that

moral and intellectual characteristics depend on structure, and yet tell

us that there is no such gulf between the structure of man and that of

the lower animals?"

I think that objection is based upon a misconception of the real

relations which exist between structure and function, between mechanism

and work. Function is the expression of molecular forces and

arrangements no doubt; but, does it follow from this, that variation in

function so depends upon variation in structure that the former is

always exactly proportioned to the latter? If there is no such relation,

if the variation in function which follows on a variation in structure,

may be enormously greater than the variation of the structure, then, you

see, the objection falls to the ground.

Take a couple of watches--made by the same maker, and as completely

alike as possible; set them upon the table, and the function of

each--which is its rate of going--will be performed in the same manner,

and you shall be able to distinguish no difference between them; but let

me take a pair of pincers, and if my hand is steady enough to do it, let

me just lightly crush together the bearings of the balance-wheel, or

force to a slightly different angle the teeth of the escapement of one

of them, and of course you know the immediate result will be that the

watch, so treated, from that moment will cease to go. But what

proportion is there between the structural alteration and the functional

result? Is it not perfectly obvious that the alteration is of the

minutest kind, yet that slight as it is, it has produced an infinite

difference in the performance of the functions of these two

instruments?

Well, now, apply that to the present question. What is it that

constitutes and makes man what he is? What is it but his power of

language--that language giving him the means of recording his

experience--making every generation somewhat wiser than its

predecessor,--more in accordance with the established order of the

universe?

What is it but this power of speech, of recording experience, which

enables men to be men--looking before and after and, in some dim sense,

understanding the working of this wondrous universe--and which

distinguishes man from the whole of the brute world? I say that this

functional difference is vast, unfathomable, and truly infinite in its

consequences; and I say at the same time, that it may depend upon

structural differences which shall be absolutely inappreciable to us

with our present means of investigation. What is this very speech that

we are talking about? I am speaking to you at this moment, but if you

were to alter, in the minutest degree, the proportion of the nervous

forces now active in the two nerves which supply the muscles of my

glottis, I should become suddenly dumb. The voice is produced only so

long as the vocal chords are parallel; and these are parallel only so

long as certain muscles contract with exact equality; and that again

depends on the equality of action of those two nerves I spoke of. So

that a change of the minutest kind in the structure of one of these

nerves, or in the structure of the part in which it originates, or of

the supply of blood to that part, or of one of the muscles to which it

is distributed, might render all of us dumb. But a race of dumb men,

deprived of all communication with those who could speak, would be

little indeed removed from the brutes. And the moral and intellectual

difference between them and ourselves would be practically infinite,

though the naturalist should not be able to find a single shadow of even

specific structural difference.

But let me dismiss this question now, and, in conclusion, let me say

that you may go away with it as my mature conviction, that Mr. Darwin's

work is the greatest contribution which has been made to biological

science since the publication of the "Règne Animal" of Cuvier, and

since that of the "History of Development," of Von Baer. I believe that

if you strip it of its theoretical part it still remains one of the

greatest encyclopædias of biological doctrine that any one man ever

brought forth; and I believe that, if you take it as the embodiment of

an hypothesis, it is destined to be the guide of biological and

psychological speculation for the next three or four generations.