THE ORIGIN OF SPECIES

[1860]

Mr. Darwin's long-standing and well-earned scientific eminence probably

renders him indifferent to that social notoriety which passes by the name

of success; but if the calm spirit of the philosopher have not yet wholly

superseded the ambition and the vanity of the carnal man within him, he

must be well satisfied with the results of his venture in publishing the

"Origin of Species." Overflowing the narrow bounds of purely scientific

circles, the "species question" divides with Italy and the Volunteers the

attention of general society. Everybody has read Mr. Darwin's book, or, at

least, has given an opinion upon its merits or demerits; pietists, whether

lay or ecclesiastic, decry it with the mild railing which sounds so

charitable; bigots denounce it with ignorant invective; old ladies of both

sexes consider it a decidedly dangerous book, and even savants, who have no

better mud to throw, quote antiquated writers to show that its author is no

better than an ape himself; while every philosophical thinker hails it as a

veritable Whitworth gun in the armoury of liberalism; and all competent

naturalists and physiologists, whatever their opinions as to the ultimate

fate of the doctrines put forth, acknowledge that the work in which they

are embodied is a solid contribution to knowledge and inaugurates a new

epoch in natural history.

Nor has the discussion of the subject been restrained within the limits of

conversation. When the public is eager and interested, reviewers must

minister to its wants; and the genuine _littérateur_ is too much in

the habit of acquiring his knowledge from the book he judges--as the

Abyssinian is said to provide himself with steaks from the ox which carries

him--to be withheld from criticism of a profound scientific work by the

mere want of the requisite preliminary scientific acquirement; while, on

the other hand, the men of science who wish well to the new views, no less

than those who dispute their validity, have naturally sought opportunities

of expressing their opinions. Hence it is not surprising that almost all

the critical journals have noticed Mr. Darwin's work at greater or less

length; and so many disquisitions, of every degree of excellence, from the

poor product of ignorance, too often stimulated by prejudice, to the fair

and thoughtful essay of the candid student of Nature, have appeared, that

it seems an almost hopeless task to attempt to say anything new upon the

question.

But it may be doubted if the knowledge and acumen of prejudged scientific

opponents, and the subtlety of orthodox special pleaders, have yet exerted

their full force in mystifying the real issues of the great controversy

which has been set afoot, and whose end is hardly likely to be seen by this

generation; so that, at this eleventh hour, and even failing anything new,

it may be useful to state afresh that which is true, and to put the

fundamental positions advocated by Mr. Darwin in such a form that they may

be grasped by those whose special studies lie in other directions. And the

adoption of this course may be the more advisable, because, notwithstanding

its great deserts, and indeed partly on account of them, the "Origin of

Species" is by no means an easy book to read--if by reading is implied the

full comprehension of an author's meaning.

We do not speak jestingly in saying that it is Mr. Darwin's misfortune to

know more about the question he has taken up than any man living.

Personally and practically exercised in zoology, in minute anatomy, in

geology; a student of geographical distribution, not on maps and in museums

only, but by long voyages and laborious collection; having largely advanced

each of these branches of science, and having spent many years in gathering

and sifting materials for his present work, the store of accurately

registered facts upon which the author of the "Origin of Species" is able

to draw at will is prodigious.

But this very superabundance of matter must have been embarrassing to a

writer who, for the present, can only put forward an abstract of his views;

and thence it arises, perhaps, that notwithstanding the clearness of the

style, those who attempt fairly to digest the book find much of it a sort

of intellectual pemmican--a mass of facts crushed and pounded into shape,

rather than held together by the ordinary medium of an obvious logical

bond; due attention will, without doubt, discover this bond, but it is

often hard to find.

Again, from sheer want of room, much has to be taken for granted which

might readily enough be proved; and hence, while the adept, who can supply

the missing links in the evidence from his own knowledge, discovers fresh

proof of the singular thoroughness with which all difficulties have been

considered and all unjustifiable suppositions avoided, at every reperusal

of Mr. Darwin's pregnant paragraphs, the novice in biology is apt to

complain of the frequency of what he fancies is gratuitous assumption.

Thus while it may be doubted if, for some years, any one is likely to be

competent to pronounce judgment on all the issues raised by Mr. Darwin,

there is assuredly abundant room for him, who, assuming the humbler, though

perhaps as useful, office of an interpreter between the "Origin of Species"

and the public, contents himself with endeavouring to point out the nature

of the problems which it discusses; to distinguish between the ascertained

facts and the theoretical views which it contains; and finally, to show the

extent to which the explanation it offers satisfies the requirements of

scientific logic. At any rate, it is this office which we purpose to

undertake in the following pages.

It may be safely assumed that our readers have a general conception of the

nature of the objects to which the word "species" is applied; but it has,

perhaps, occurred to a few, even to those who are naturalists _ex

professo_, to reflect, that, as commonly employed, the term has a double

sense and denotes two very different orders of relations. When we call a

group of animals, or of plants, a species, we may imply thereby, either

that all these animals or plants have some common peculiarity of form or

structure; or, we may mean that they possess some common functional

character. That part of biological science which deals with form and

structure is called Morphology--that which concerns itself with function,

Physiology--so that we may conveniently speak of these two senses, or

aspects, of "species"--the one as morphological, the other as

physiological. Regarded from the former point of view, a species is nothing

more than a kind of animal or plant, which is distinctly definable from all

others, by certain constant, and not merely sexual, morphological

peculiarities. Thus horses form a species, because the group of animals to

which that name is applied is distinguished from all others in the world by

the following constantly associated characters. They have--1, A vertebral

column; 2, Mammae; 3, A placental embryo; 4, Four legs; 5, A single

well-developed toe in each foot provided with a hoof; 6, A bushy tail; and

7, Callosities on the inner sides of both the fore and the hind legs. The

asses, again, form a distinct species, because, with the same characters,

as far as the fifth in the above list, all asses have tufted tails, and

have callosities only on the inner side of the fore-legs. If animals were

discovered having the general characters of the horse, but sometimes with

callosities only on the fore-legs, and more or less tufted tails; or

animals having the general characters of the ass, but with more or less

bushy tails, and sometimes with callosities on both pairs of legs, besides

being intermediate in other respects--the two species would have to be

merged into one. They could no longer be regarded as morphologically

distinct species, for they would not be distinctly definable one from the

other.

However bare and simple this definition of species may appear to be, we

confidently appeal to all practical naturalists, whether zoologists,

botanists, or palaeontologists, to say if, in the vast majority of cases,

they know, or mean to affirm, anything more of the group of animals or

plants they so denominate than what has just been stated. Even the most

decided advocates of the received doctrines respecting species admit this.

"I apprehend," says Professor Owen, [Footnote: "On the Osteology of the

Chimpanzees and Orangs"; _Transactions of the Zoological Society_,

1858.] "that few naturalists nowadays, in describing and proposing a name

for what they call 'a new _species_,' use that term to signify what

was meant by it twenty or thirty years ago; that is, an originally distinct

creation, maintaining its primitive distinction by obstructive generative

peculiarities. The proposer of the new species now intends to state no more

than he actually knows; as, for example, that the differences on which he

founds the specific character are constant in individuals of both sexes, so

far as observation has reached; and that they are not due to domestication

or to artificially superinduced external circumstances, or to any outward

influence within his cognizance; that the species is wild, or is such as it

appears by Nature."

If we consider, in fact, that by far the largest proportion of recorded

existing species are known only by the study of their skins, or bones, or

other lifeless exuviae; that we are acquainted with none, or next to none,

of their physiological peculiarities, beyond those which can be deduced

from their structure, or are open to cursory observation; and that we

cannot hope to learn more of any of those extinct forms of life which now

constitute no inconsiderable proportion of the known Flora and Fauna of the

world: it is obvious that the definitions of these species can be only of a

purely structural, or morphological, character. It is probable that

naturalists would have avoided much confusion of ideas if they had more

frequently borne the necessary limitations of our knowledge in mind. But

while it may safely be admitted that we are acquainted with only the

morphological characters of the vast majority of species--the functional or

physiological, peculiarities of a few have been carefully investigated, and

the result of that study forms a large and most interesting portion of the

physiology of reproduction.

The student of Nature wonders the more and is astonished the less, the more

conversant he becomes with her operations; but of all the perennial

miracles she offers to his inspection, perhaps the most worthy of

admiration is the development of a plant or of an animal from its embryo.

Examine the recently laid egg of some common animal, such as a salamander

or newt. It is a minute spheroid in which the best microscope will reveal

nothing but a structureless sac, enclosing a glairy fluid, holding granules

in suspension. [Footnote: When this sentence was written, it was generally

believed that the original nucleus of the egg (the germinal vesicle)

disappeared. 1893.] But strange possibilities lie dormant in that

semi-fluid globule. Let a moderate supply of warmth reach its watery

cradle, and the plastic matter undergoes changes so rapid, yet so steady

and purposelike in their succession, that one can only compare them to

those operated by a skilled modeller upon a formless lump of clay. As with

an invisible trowel, the mass is divided and subdivided into smaller and

smaller portions, until it is reduced to an aggregation of granules not too

large to build withal the finest fabrics of the nascent organism. And,

then, it is as if a delicate finger traced out the line to be occupied by

the spinal column, and moulded the contour of the body; pinching up the

head at one end, the tail at the other, and fashioning flank and limb into

due salamandrine proportions, in so artistic a way, that, after watching

the process hour by hour, one is almost involuntarily possessed by the

notion, that some more subtle aid to vision than an achromatic, would show

the hidden artist, with his plan before him, striving with skilful

manipulation to perfect his work.

As life advances, and the young amphibian ranges the waters, the terror of

his insect contemporaries, not only are the nutritious particles supplied

by its prey, by the addition of which to its frame, growth takes place,

laid down, each in its proper spot, and in such due proportion to the rest,

as to reproduce the form, the colour, and the size, characteristic of the

parental stock; but even the wonderful powers of reproducing lost parts

possessed by these animals are controlled by the same governing tendency.

Cut off the legs, the tail, the jaws, separately or all together, and, as

Spallanzani showed long ago, these parts not only grow again, but the

redintegrated limb is formed on the same type as those which were lost. The

new jaw, or leg, is a newt's, and never by any accident more like that of a

frog. What is true of the newt is true of every animal and of every plant;

the acorn tends to build itself up again into a woodland giant such as that

from whose twig it fell; the spore of the humblest lichen reproduces the

green or brown incrustation which gave it birth; and at the other end of

the scale of life, the child that resembled neither the paternal nor the

maternal side of the house would be regarded as a kind of monster.

So that the one end to which, in all living beings, the formative impulse

is tending--the one scheme which the Archæus of the old speculators strives

to carry out, seems to be to mould the offspring into the likeness of the

parent. It is the first great law of reproduction, that the offspring tends

to resemble its parent or parents, more closely than anything else.

Science will some day show us how this law is a necessary consequence of

the more general laws which govern matter; but, for the present, more can

hardly be said than that it appears to be in harmony with them. We know

that the phænomena of vitality are not something apart from other physical

phænomena, but one with them; and matter and force are the two names of the

one artist who fashions the living as well as the lifeless. Hence living

bodies should obey the same great laws as other matter--nor, throughout

Nature, is there a law of wider application than this, that a body impelled

by two forces takes the direction of their resultant. But living bodies may

be regarded as nothing but extremely complex bundles of forces held in a

mass of matter, as the complex forces of a magnet are held in the steel by

its coercive force; and, since the differences of sex are comparatively

slight, or, in other words, the sum of the forces in each has a very

similar tendency, their resultant, the offspring, may reasonably be

expected to deviate but little from a course parallel to either, or to

both.

Represent the reason of the law to ourselves by what physical metaphor or

analogy we will, however, the great matter is to apprehend its existence

and the importance of the consequences deducible from it. For things which

are like to the same are like to one another; and if, in a great series of

generations, every offspring is like its parent, it follows that all the

offspring and all the parents must be like one another; and that, given an

original parental stock, with the opportunity of undisturbed

multiplication, the law in question necessitates the production, in course

of time, of an indefinitely large group, the whole of the members of which

are at once very similar and are blood relations, having descended from the

same parent, or pair of parents. The proof that all the members of any

given group of animals, or plants, had thus descended, would be ordinarily

considered sufficient to entitle them to the rank of physiological species,

for most physiologists consider species to be definable as "the offspring

of a single primitive stock."

But though it is quite true that all those groups we call species

_may_, according to the known laws of reproduction, have descended

from a single stock, and though it is very likely they really have done so,

yet this conclusion rests on deduction and can hardly hope to establish

itself upon a basis of observation. And the primitiveness of the supposed

single stock, which, after all, is the essential part of the matter, is not

only a hypothesis, but one which has not a shadow of foundation, if by

"primitive" be meant "independent of any other living being." A scientific

definition, of which an unwarrantable hypothesis forms an essential part,

carries its condemnation within itself; but, even supposing such a

definition were, in form, tenable, the physiologist who should attempt to

apply it in Nature would soon find himself involved in great, if not

inextricable, difficulties. As we have said, it is indubitable that

offspring _tend_ to resemble the parental organism, but it is equally

true that the similarity attained never amounts to identity either in form

or in structure. There is always a certain amount of deviation, not only

from the precise characters of a single parent, but when, as in most

animals and many plants, the sexes are lodged in distinct individuals, from

an exact mean between the two parents. And indeed, on general principles,

this slight deviation seems as intelligible as the general similarity, if

we reflect how complex the co-operating "bundles of forces" are, and how

improbable it is that, in any case, their true resultant shall coincide

with any mean between the more obvious characters of the two parents.

Whatever be its cause, however, the co-existence of this tendency to minor

variation with the tendency to general similarity, is of vast importance in

its bearing on the question of the origin of species.

As a general rule, the extent to which an offspring differs from its parent

is slight enough; but, occasionally, the amount of difference is much more

strongly marked, and then the divergent offspring receives the name of a

Variety. Multitudes, of what there is every reason to believe are such

varieties, are known, but the origin of very few has been accurately

recorded, and of these we will select two as more especially illustrative

of the main features of variation. The first of them is that of the "Ancon"

or "Otter" sheep, of which a careful account is given by Colonel David

Humphreys, F.R.S., in a letter to Sir Joseph Banks, published in the

"Philosophical Transactions" for 1813. It appears that one Seth Wright, the

proprietor of a farm on the banks of the Charles River, in Massachusetts,

possessed a flock of fifteen ewes and a ram of the ordinary kind. In the

year 1791, one of the ewes presented her owner with a male lamb, differing,

for no assignable reason, from its parents by a proportionally long body

and short bandy legs, whence it was unable to emulate its relatives in

those sportive leaps over the neighbours' fences, in which they were in the

habit of indulging, much to the good farmer's vexation.

The second case is that detailed by a no less unexceptionable authority

than Réaumur, in his "Art de faire éclore les Poulets." A Maltese couple,

named Kelleia, whose hands and feet were constructed upon the ordinary

human model, had born to them a son, Gratio, who possessed six perfectly

movable fingers on each hand, and six toes, not quite so well formed, on

each foot. No cause could be assigned for the appearance of this unusual

variety of the human species.

Two circumstances are well worthy of remark in both these cases. In each,

the variety appears to have arisen in full force, and, as it were, _per

saltum_; a wide and definite difference appearing, at once, between the

Ancon ram and the ordinary sheep; between the six-fingered and six-toed

Gratio Kelleia and ordinary men. In neither case is it possible to point

out any obvious reason for the appearance of the variety. Doubtless there

were determining causes for these as for all other phenomena; but they do

not appear, and we can be tolerably certain that what are ordinarily

understood as changes in physical conditions, as in climate, in food, or

the like, did not take place and had nothing to do with the matter. It was

no case of what is commonly called adaptation to circumstances; but, to use

a conveniently erroneous phrase, the variations arose spontaneously. The

fruitless search after final causes leads their pursuers a long way; but

even those hardy teleologists, who are ready to break through all the laws

of physics in chase of their favourite will-o'-the-wisp, may be puzzled to

discover what purpose could be attained by the stunted legs of Seth

Wright's ram or the hexadactyle members of Gratio Kelleia.

Varieties then arise we know not why; and it is more than probable that the

majority of varieties have arisen in this "spontaneous" manner, though we

are, of course, far from denying that they may be traced, in some cases, to

distinct external influences; which are assuredly competent to alter the

character of the tegumentary covering, to change colour, to increase or

diminish the size of muscles, to modify constitution, and, among plants, to

give rise to the metamorphosis of stamens into petals, and so forth. But

however they may have arisen, what especially interests us at present is,

to remark that, once in existence, many varieties obey the fundamental law

of reproduction that like tends to produce like; and their offspring

exemplify it by tending to exhibit the same deviation from the parental

stock as themselves. Indeed, there seems to be, in many instances, a

prepotent influence about a newly-arisen variety which gives it what one

may call an unfair advantage over the normal descendants from the same

stock. This is strikingly exemplified by the case of Gratio Kelleia, who

married a woman with the ordinary pentadactyle extremities, and had by her

four children, Salvator, George, André, and Marie. Of these children

Salvator, the eldest boy, had six fingers and six toes, like his father;

the second and third, also boys, had five fingers and five toes, like their

mother, though the hands and feet of George were slightly deformed. The

last, a girl, had five fingers and five toes, but the thumbs were slightly

deformed. The variety thus reproduced itself purely in the eldest, while

the normal type reproduced itself purely in the third, and almost purely in

the second and last: so that it would seem, at first, as if the normal type

were more powerful than the variety. But all these children grew up and

intermarried with normal wives and husband, and then, note what took place:

Salvator had four children, three of whom exhibited the hexadactyle members

of their grandfather and father, while the youngest had the pentadactyle

limbs of the mother and grandmother; so that here, notwithstanding a double

pentadactyle dilution of the blood, the hexadactyle variety had the best of

it. The same pre-potency of the variety was still more markedly exemplified

in the progeny of two of the other children, Marie and George. Marie (whose

thumbs only were deformed) gave birth to a boy with six toes, and three

other normally formed children; but George, who was not quite so pure a

pentadactyle, begot, first, two girls, each of whom had six fingers and

toes; then a girl with six fingers on each hand and six toes on the right

foot, but only five toes on the left; and lastly, a boy with only five

fingers and toes. In these instances, therefore, the variety, as it were,

leaped over one generation to reproduce itself in full force in the next.

Finally, the purely pentadactyle André was the father of many children, not

one of whom departed from the normal parental type.

If a variation which approaches the nature of a monstrosity can strive thus

forcibly to reproduce itself, it is not wonderful that less aberrant

modifications should tend to be preserved even more strongly; and the

history of the Ancon sheep is, in this respect, particularly instructive.

With the "'cuteness" characteristic of their nation, the neighbours of the

Massachusetts farmer imagined it would be an excellent thing if all his

sheep were imbued with the stay-at-home tendencies enforced by Nature upon

the newly-arrived ram; and they advised Wright to kill the old patriarch of

his fold, and install the Ancon ram in his place. The result justified

their sagacious anticipations, and coincided very nearly with what occurred

to the progeny of Gratio Kelleia. The young lambs were almost always either

pure Ancons, or pure ordinary sheep.[Footnote: Colonel Humphreys'

statements are exceedingly explicit on this point:--. "When an Ancon ewe is

impregnated by a common ram, the increase resembles wholly either the ewe

or the ram. The increase of the common ewe impregnated by an Ancon ram

follows entirely the one or the other, without blending any of the

distinguishing and essential peculiarities of both. Frequent instances have

happened where common ewes have had twins by Ancon rams, when one exhibited

the complete marks and features of the ewe, the other of the ram. The

contrast has been rendered singularly striking, when one short-legged and

one long-legged lamb, produced at a birth, have been seen sucking the dam

at the same time."--_Philosophical Transactions_, 1813, Ft. I. pp. 89,

90.] But when sufficient Ancon sheep were obtained to interbreed with one

another, it was found that the offspring was always pure Ancon. Colonel

Humphreys, in fact, states that he was acquainted with only "one

questionable case of a contrary nature." Here, then, is a remarkable and

well-established instance, not only of a very distinct race being

established _per saltum_, but of that race breeding "true" at once,

and showing no mixed forms, even when crossed with another breed.

By taking care to select Ancons of both sexes, for breeding from, it thus

became easy to establish an extremely well-marked race; so peculiar that,

even when herded with other sheep, it was noted that the Ancons kept

together. And there is every reason to believe that the existence of this

breed might have been indefinitely protracted; but the introduction of the

Merino sheep, which were not only very superior to the Ancons in wool and

meat, but quite as quiet and orderly, led to the complete neglect of the

new breed, so that, in 1813, Colonel Humphreys found it difficult to obtain

the specimen, the skeleton of which was presented to Sir Joseph Banks. We

believe that, for many years, no remnant of it has existed in the United

States.

Gratio Kelleia was not the progenitor of a race of six-fingered men, as

Seth Wright's ram became a nation of Ancon sheep, though the tendency of

the variety to perpetuate itself appears to have been fully as strong in

the one case as in the other. And the reason of the difference is not far

to seek. Seth Wright took care not to weaken the Ancon blood by matching

his Ancon ewes with any but males of the same variety, while Gratio

Kelleia's sons were too far removed from the patriarchal times to

intermarry with their sisters; and his grand-children seem not to have been

attracted by their six-fingered cousins. In other words, in the one example

a race was produced, because, for several generations, care was taken to

_select_ both parents of the breeding stock from animals exhibiting a

tendency to vary in the same direction; while, in the other, no race was

evolved, because no such selection was exercised. A race is a propagated

variety; and as, by the laws of reproduction, offspring tend to assume the

parental forms, they will be more likely to propagate a variation exhibited

by both parents than that possessed by only one.

There is no organ of the body of an animal which may not, and does not,

occasionally, vary more or less from the normal type; and there is no

variation which may not be transmitted and which, if selectively

transmitted, may not become the foundation of a race. This great truth,

sometimes forgotten by philosophers, has long been familiar to practical

agriculturists and breeders; and upon it rest all the methods of improving

the breeds of domestic animals, which, for the last century, have been

followed with so much success in England. Colour, form, size, texture of

hair or wool, proportions of various parts, strength or weakness of

constitution, tendency to fatten or to remain lean, to give much or little

milk, speed, strength, temper, intelligence, special instincts; there is

not one of these characters the transmission of which is not an every-day

occurrence within the experience of cattle-breeders, stock-farmers,

horse-dealers, and dog and poultry fanciers. Nay, it is only the other day

that an eminent physiologist, Dr. Brown-Séquard, communicated to the Royal

Society his discovery that epilepsy, artificially produced in guinea-pigs,

by a means which he has discovered, is transmitted to their offspring.

[Footnote: Compare Weismann's _Essays Upon Heredity_, p. 310, _et

seq_. 1893.]

But a race, once produced, is no more a fixed and immutable entity than the

stock whence it sprang; variations arise among its members, and as these

variations are transmitted like any others, new races may be developed out

of the pre-existing one _ad infinitum_, or, at least, within any limit

at present determined. Given sufficient time and sufficiently careful

selection, and the multitude of races which may arise from a common stock

is as astonishing as are the extreme structural differences which they may

present. A remarkable example of this is to be found in the rock-pigeon,

which Mr. Darwin has, in our opinion, satisfactorily demonstrated to be the

progenitor of all our domestic pigeons, of which there are certainly more

than a hundred well-marked races. The most noteworthy of these races are,

the four great stocks known to the "fancy" as tumblers, pouters, carriers,

and fantails; birds which not only differ most singularly in size, colour,

and habits, but in the form of the beak and of the skull; in the

proportions of the beak to the skull; in the number of tail-feathers; in

the absolute and relative size of the feet; in the presence or absence of

the uropygial gland; in the number of vertebræ in the back; in short, in

precisely those characters in which the genera and species of birds differ

from one another.

And it is most remarkable and instructive to observe, that none of these

races can be shown to have been originated by the action of changes in what

are commonly called external circumstances, upon the wild rock-pigeon. On

the contrary, from time immemorial pigeon-fanciers have had essentially

similar methods of treating their pets, which have been housed, fed,

protected and cared for in much the same way in all pigeonries. In fact,

there is no case better adapted than that of the pigeons to refute the

doctrine which one sees put forth on high authority, that "no other

characters than those founded on the development of bone for the attachment

of muscles" are capable of variation. In precise contradiction of this

hasty assertion, Mr. Darwin's researches prove that the skeleton of the

wings in domestic pigeons has hardly varied at all from that of the wild

type; while, on the other hand, it is in exactly those respects, such as

the relative length of the beak and skull, the number of the vertebrae, and

the number of the tail-feathers, in which muscular exertion can have no

important influence, that the utmost amount of variation has taken place.

We have said that the following out of the properties exhibited by

physiological species would lead us into difficulties, and at this point

they begin to be obvious; for if, as the result of spontaneous variation

and of selective breeding, the progeny of a common stock may become

separated into groups distinguished from one another by constant, not

sexual, morphological characters, it is clear that the physiological

definition of species is likely to clash with the morphological definition.

No one would hesitate to describe the pouter and the tumbler as distinct

species, if they were found fossil, or if their skins and skeletons were

imported, as those of exotic wild birds commonly are--and without doubt, if

considered alone, they are good and distinct morphological species. On the

other hand, they are not physiological species, for they are descended from

a common stock, the rock-pigeon.

Under these circumstances, as it is admitted on all sides that races occur

in Nature, how are we to know whether any apparently distinct animals are

really of different physiological species, or not, seeing that the amount

of morphological difference is no safe guide? Is there any test of a

physiological species? The usual answer of physiologists is in the

affirmative. It is said that such a test is to be found in the phænomena of

hybridisation--in the results of crossing races, as compared with the

results of crossing species.

So far as the evidence goes at present, individuals, of what are certainly

known to be mere races produced by selection, however distinct they may

appear to be, not only breed freely together, but the offspring of such

crossed races are perfectly fertile with one another. Thus, the spaniel and

the greyhound, the dray-horse and the Arab, the pouter and the tumbler,

breed together with perfect freedom, and their mongrels, if matched with

other mongrels of the same kind, are equally fertile.

On the other hand, there can be no doubt that the individuals of many

natural species are either absolutely infertile if crossed with individuals

of other species, or, if they give rise to hybrid offspring, the hybrids so

produced are infertile when paired together. The horse and the ass, for

instance, if so crossed, give rise to the mule, and there is no certain

evidence of offspring ever having been produced by a male and female mule.

The unions of the rock-pigeon and the ring-pigeon appear to be equally

barren of result. Here, then, says the physiologist, we have a means of

distinguishing any two true species from any two varieties. If a male and a

female, selected from each group, produce offspring, and that offspring is

fertile with others produced in the same way, the groups are races and not

species. If, on the other hand, no result ensues, or if the offspring are

infertile with others produced in the same way, they are true physiological

species. The test would be an admirable one, if, in the first place, it

were always practicable to apply it, and if, in the second, it always

yielded results susceptible of a definite interpretation. Unfortunately, in

the great majority of cases, this touchstone for species is wholly

inapplicable.

The constitution of many wild animals is so altered by confinement that

they will not breed even with their own females, so that the negative

results obtained from crosses are of no value; and the antipathy of wild

animals of different species for one another, or even of wild and tame

members of the same species, is ordinarily so great, that it is hopeless to

look for such unions in Nature. The hermaphrodism of most plants, the

difficulty in the way of insuring the absence of their own or the proper

working of other pollen, are obstacles of no less magnitude in applying the

test to them. And, in both animals and plants, is super-added the further

difficulty, that experiments must be continued over a long time for the

purpose of ascertaining the fertility of the mongrel or hybrid progeny, as

well as of the first crosses from which they spring.

Not only do these great practical difficulties lie in the way of applying

the hybridisation test, but even when this oracle can be questioned, its

replies are sometimes as doubtful as those of Delphi. For example, cases

are cited by Mr. Darwin, of plants which are more fertile with the pollen

of another species than with their own; and there are others, such as

certain _Fuci,_ the male element of which will fertilise the ovule of

a plant of distinct species, while the males of the latter species are

ineffective with the females of the first. So that, in the last-named

instance, a physiologist, who should cross the two species in one way,

would decide that they were true species; while another, who should cross

them in the reverse way, would, with equal justice, according to the rule,

pronounce them to be mere races. Several plants, which there is great

reason to believe are mere varieties, are almost sterile when crossed;

while both animals and plants, which have always been regarded by

naturalists as of distinct species, turn out, when the test is applied, to

be perfectly fertile. Again, the sterility or fertility of crosses seems to

bear no relation to the structural resemblances or differences of the

members of any two groups.

Mr. Darwin has discussed this question with singular ability and

circumspection, and his conclusions are summed up as follows, at page 276

of his work:--

"First crosses between forms sufficiently distinct to be ranked as species,

and their hybrids, are very generally, but not universally, sterile. The

sterility is of all degrees, and is often so slight that the two most

careful experimentalists who have ever lived have come to diametrically

opposite conclusions in ranking forms by this test. The sterility is

innately variable in individuals of the same species, and is eminently

susceptible of favourable and unfavourable conditions. The degree of

sterility does not strictly follow systematic affinity, but is governed by

several curious and complex laws. It is generally different and sometimes

widely different, in reciprocal crosses between the same two species. It is

not always equal in degree in a first cross, and in the hybrid produced

from this cross.

"In the same manner as in grafting trees, the capacity of one species or

variety to take on another is incidental on generally unknown differences

in their vegetative systems; so in crossing, the greater or less facility

of one species to unite with another is incidental on unknown differences

in their reproductive systems. There is no more reason to think that

species have been specially endowed with various degrees of sterility to

prevent them crossing and breeding in Nature, than to think that trees have

been specially endowed with various and somewhat analogous degrees of

difficulty in being grafted together, in order to prevent them becoming

inarched in our forests.

"The sterility of first crosses between pure species, which have their

reproductive systems perfect, seems to depend on several circumstances; in

some cases largely on the early death of the embryo. The sterility of

hybrids which have their reproductive systems imperfect, and which have had

this system and their whole organisation disturbed by being compounded of

two distinct species, seems closely allied to that sterility which so

frequently affects pure species when their natural conditions of life have

been disturbed. This view is supported by a parallelism of another kind:

namely, that the crossing of forms, only slightly different, is favourable

to the vigour and fertility of the offspring; and that slight changes in

the conditions of life are apparently favourable to the vigour and

fertility of all organic beings. It is not surprising that the degree of

difficulty in uniting two species, and the degree of sterility of their

hybrid offspring, should generally correspond, though due to distinct

causes; for both depend on the amount of difference of some kind between

the species which are crossed. Nor is it surprising that the facility of

effecting a first cross, the fertility of hybrids produced from it, and the

capacity of being grafted together--though this latter capacity evidently

depends on widely different circumstances--should all run to a certain

extent parallel with the systematic affinity of the forms which are

subjected to experiment; for systematic affinity attempts to express all

kinds of resemblance between all species.

"First crosses between forms known to be varieties, or sufficiently alike

to be considered as varieties, and their mongrel offspring, are very

generally, but not quite universally, fertile. Nor is this nearly general

and perfect fertility surprising, when we remember how liable we are to

argue in a circle with respect to varieties in a state of Nature; and when

we remember that the greater number of varieties have been produced under

domestication by the selection of mere external differences, and not of

differences in the reproductive system. In all other respects, excluding

fertility, there is a close general resemblance between hybrids and

mongrels."--Pp. 276-8.

We fully agree with the general tenor of this weighty passage; but forcible

as are these arguments, and little as the value of fertility or infertility

as a test of species may be, it must not be forgotten that the really

important fact, so far as the inquiry into the origin of species goes, is,

that there are such things in Nature as groups of animals and of plants,

the members of which are incapable of fertile union with those of other

groups; and that there are such things as hybrids, which are absolutely

sterile when crossed with other hybrids. For, if such phænomena as these

were exhibited by only two of those assemblages of living objects, to which

the name of species (whether it be used in its physiological or in its

morphological sense) is given, it would have to be accounted for by any

theory of the origin of species, and every theory which could not account

for it would be, so far, imperfect.

Up to this point, we have been dealing with matters of fact, and the

statements which we have laid before the reader would, to the best of our

knowledge, be admitted to contain a fair exposition of what is at present

known respecting the essential properties of species, by all who have

studied the question. And whatever may be his theoretical views, no

naturalist will probably be disposed to demur to the following summary of

that exposition:--

Living beings, whether animals or plants, are divisible into multitudes of

distinctly definable kinds, which are morphological species. They are also

divisible into groups of individuals, which breed freely together, tending

to reproduce their like, and are physiological species. Normally resembling

their parents, the offspring of members of these species are still liable

to vary; and the variation may be perpetuated by selection, as a race,

which race, in many cases, presents all the characteristics of a

morphological species. But it is not as yet proved that a race ever

exhibits, when crossed with another race of the same species, those

phænomena of hybridisation which are exhibited by many species when crossed

with other species. On the other hand, not only is it not proved that all

species give rise to hybrids infertile _inter se_, but there is much

reason to believe that, in crossing, species exhibit every gradation from

perfect sterility to perfect fertility.

Such are the most essential characteristics of species. Even were man not

one of them--a member of the same system and subject to the same laws--the

question of their origin, their causal connexion, that is, with the other

phænomena of the universe, must have attracted his attention, as soon as

his intelligence had raised itself above the level of his daily wants.

Indeed history relates that such was the case, and has embalmed for us the

speculations upon the origin of living beings, which were among the

earliest products of the dawning intellectual activity of man. In those

early days positive knowledge was not to be had, but the craving after it

needed, at all hazards, to be satisfied, and according to the country, or

the turn of thought, of the speculator, the suggestion that all living

things arose from the mud of the Nile, from a primeval egg, or from some

more anthropomorphic agency, afforded a sufficient resting-place for his

curiosity. The myths of Paganism are as dead as Osiris or Zeus, and the man

who should revive them, in opposition to the knowledge of our time, would

be justly laughed to scorn; but the coeval imaginations current among the

rude inhabitants of Palestine, recorded by writers whose very name and age

are admitted by every scholar to be unknown, have unfortunately not yet

shared their fate, but, even at this day, are regarded by nine-tenths of

the civilised world as the authoritative standard of fact and the criterion

of the justice of scientific conclusions, in all that relates to the origin

of things, and, among them, of species. In this nineteenth century, as at

the dawn of modern physical science, the cosmogony of the semi-barbarous

Hebrew is the incubus of the philosopher and the opprobrium of the

orthodox. Who shall number the patient and earnest seekers after truth,

from the days of Galileo until now, whose lives have been embittered and

their good name blasted by the mistaken zeal of Bibliolaters? Who shall

count the host of weaker men whose sense of truth has been destroyed in the

effort to harmonise impossibilities--whose life has been wasted in the

attempt to force the generous new wine of Science into the old bottles of

Judaism, compelled by the outcry of the same strong party?

It is true that if philosophers have suffered, their cause has been amply

avenged. Extinguished theologians lie about the cradle of every science as

the strangled snakes beside that of Hercules; and history records that

whenever science and orthodoxy have been fairly opposed, the latter has

been forced to retire from the lists, bleeding and crushed if not

annihilated; scotched, if not slain. But orthodoxy is the Bourbon of the

world of thought. It learns not, neither can it forget; and though, at

present, bewildered and afraid to move, it is as willing as ever to insist

that the first chapter of Genesis contains the beginning and the end of

sound science; and to visit, with such petty thunderbolts as its

half-paralysed hands can hurl, those who refuse to degrade Nature to the

level of primitive Judaism.

Philosophers, on the other hand, have no such aggressive tendencies. With

eyes fixed on the noble goal to which "per aspera et ardua" they tend, they

may, now and then, be stirred to momentary wrath by the unnecessary

obstacles with which the ignorant, or the malicious, encumber, if they

cannot bar, the difficult path; but why should their souls be deeply vexed?

The majesty of Fact is on their side, and the elemental forces of Nature

are working for them. Not a star comes to the meridian at its calculated

time but testifies to the justice of their methods--their beliefs are "one

with the falling rain and with the growing corn." By doubt they are

established, and open inquiry is their bosom friend. Such men have no fear

of traditions however venerable, and no respect for them when they become

mischievous and obstructive; but they have better than mere antiquarian

business in hand, and if dogmas, which ought to be fossil but are not, are

not forced upon their notice, they are too happy to treat them as

non-existent.

* * * * *

The hypotheses respecting the origin of species which profess to stand upon

a scientific basis, and, as such, alone demand serious attention, are of

two kinds. The one, the "special creation" hypothesis, presumes every

species to have originated from one or more stocks, these not being the

result of the modification of any other form of living matter--or arising

by natural agencies--but being produced, as such, by a supernatural

creative act.

The other, the so-called "transmutation" hypothesis, considers that all

existing species are the result of the modification of pre-existing

species, and those of their predecessors, by agencies similar to those

which at the present day produce varieties and races, and therefore in an

altogether natural way; and it is a probable, though not a necessary

consequence of this hypothesis, that all living beings have arisen from a

single stock. With respect to the origin of this primitive stock, or

stocks, the doctrine of the origin of species is obviously not necessarily

concerned. The transmutation hypothesis, for example, is perfectly

consistent either with the conception of a special creation of the

primitive germ, or with the supposition of its having arisen, as a

modification of inorganic matter, by natural causes.

The doctrine of special creation owes its existence very largely to the

supposed necessity of making science accord with the Hebrew cosmogony; but

it is curious to observe that, as the doctrine is at present maintained by

men of science, it is as hopelessly inconsistent with the Hebrew view as

any other hypothesis.

If there be any result which has come more clearly out of geological

investigation than another, it is, that the vast series of extinct animals

and plants is not divisible, as it was once supposed to be, into distinct

groups, separated by sharply-marked boundaries. There are no great gulfs

between epochs and formations--no successive periods marked by the

appearance of plants, of water animals, and of land animals, _en

masse_. Every year adds to the list of links between what the older

geologists supposed to be widely separated epochs: witness the crags

linking the drift with older tertiaries; the Maestricht beds linking the

tertiaries with the chalk; the St. Cassian beds exhibiting an abundant

fauna of mixed mesozoic and palaeozoic types, in rocks of an epoch once

supposed to be eminently poor in life; witness, lastly, the incessant

disputes as to whether a given stratum shall be reckoned devonian or

carboniferous, silurian or devonian, cambrian or silurian.

This truth is further illustrated in a most interesting manner by the

impartial and highly competent testimony of M. Pictet, from whose

calculations of what percentage of the genera of animals, existing in any

formation, lived during the preceding formation, it results that in no case

is the proportion less than _one-third_, or 33 per cent. It is the

triassic formation, or the commencement of the mesozoic epoch, which has

received the smallest inheritance from preceding ages. The other formations

not uncommonly exhibit 60, 80, or even 94 per cent, of genera in common

with those whose remains are imbedded in their predecessor. Not only is

this true, but the subdivisions of each formation exhibit new species

characteristic of, and found only in, them; and, in many cases, as in the

lias for example, the separate beds of these subdivisions are distinguished

by well-marked and peculiar forms of life. A section, a hundred feet thick,

will exhibit, at different heights, a dozen species of ammonite, none of

which passes beyond its particular zone of limestone, or clay, into the

zone below it or into that above it; so that those who adopt the doctrine

of special creation must be prepared to admit, that at intervals of time,

corresponding with the thickness of these beds, the Creator thought fit to

interfere with the natural course of events for the purpose of making a new

ammonite. It is not easy to transplant oneself into the frame of mind of

those who can accept such a conclusion as this, on any evidence short of

absolute demonstration; and it is difficult to see what is to be gained by

so doing, since, as we have said, it is obvious that such a view of the

origin of living beings is utterly opposed to the Hebrew cosmogony.

Deserving no aid from the powerful arm of Bibliolatry, then, does the

received form of the hypothesis of special creation derive any support from

science or sound logic? Assuredly not much. The arguments brought forward

in its favour all take one form: If species were not supernaturally

created, we cannot understand the facts _x_, or _y_, or _z_;

we cannot understand the structure of animals or plants, unless we suppose

they were contrived for special ends; we cannot understand the structure of

the eye, except by supposing it to have been made to see with; we cannot

understand instincts, unless we suppose animals to have been miraculously

endowed with them.

As a question of dialectics, it must be admitted that this sort of

reasoning is not very formidable to those who are not to be frightened by

consequences. It is an _argumentum ad ignorantiam_--take this

explanation or be ignorant. But suppose we prefer to admit our ignorance

rather than adopt a hypothesis at variance with all the teachings of

Nature? Or, suppose for a moment we admit the explanation, and then

seriously ask ourselves how much the wiser are we; what does the

explanation explain? Is it any more than a grandiloquent way of announcing

the fact, that we really know nothing about the matter? A phenomenon is

explained when it is shown to be a case of some general law of Nature; but

the supernatural interposition of the Creator can, by the nature of the

case, exemplify no law, and if species have really arisen in this way, it

is absurd to attempt to discuss their origin.

Or, lastly, let us ask ourselves whether any amount of evidence which the

nature of our faculties permits us to attain, can justify us in asserting

that any phenomenon is out of the reach of natural causation. To this end

it is obviously necessary that we should know all the consequences to which

all possible combinations, continued through unlimited time, can give rise.

If we knew these, and found none competent to originate species, we should

have good ground for denying their origin by natural causation. Till we

know them, any hypothesis is better than one which involves us in such

miserable presumption.

But the hypothesis of special creation is not only a mere specious mask for

our ignorance; its existence in Biology marks the youth and imperfection of

the science. For what is the history of every science but the history of

the elimination of the notion of creative, or other interferences, with the

natural order of the phænomena which are the subject-matter of that

science? When Astronomy was young "the morning stars sang together for

joy," and the planets were guided in their courses by celestial hands. Now,

the harmony of the stars has resolved itself into gravitation according to

the inverse squares of the distances, and the orbits of the planets are

deducible from the laws of the forces which allow a schoolboy's stone to

break a window. The lightning was the angel of the Lord; but it has pleased

Providence, in these modern times, that science should make it the humble

messenger of man, and we know that every flash that shimmers about the

horizon on a summer's evening is determined by ascertainable conditions,

and that its direction and brightness might, if our knowledge of these were

great enough, have been calculated.

The solvency of great mercantile companies rests on the validity of the

laws which have been ascertained to govern the seeming irregularity of that

human life which the moralist bewails as the most uncertain of things;

plague, pestilence, and famine are admitted, by all but fools, to be the

natural result of causes for the most part fully within human control, and

not the unavoidable tortures inflicted by wrathful Omnipotence upon His

helpless handiwork.

Harmonious order governing eternally continuous progress--the web and woof

of matter and force interweaving by slow degrees, without a broken thread,

that veil which lies between us and the Infinite--that universe which alone

we know or can know; such is the picture which science draws of the world,

and in proportion as any part of that picture is in unison with the rest,

so may we feel sure that it is rightly painted. Shall Biology alone remain

out of harmony with her sister sciences?

Such arguments against the hypothesis of the direct creation of species as

these are plainly enough deducible from general considerations; but there

are, in addition, phenomena exhibited by species themselves, and yet not so

much a part of their very essence as to have required earlier mention,

which are in the highest degree perplexing, if we adopt the popularly

accepted hypothesis. Such are the facts of distribution in space and in

time; the singular phenomena brought to light by the study of development;

the structural relations of species upon which our systems of

classification are founded; the great doctrines of philosophical anatomy,

such as that of homology, or of the community of structural plan exhibited

by large groups of species differing very widely in their habits and

functions.

The species of animals which inhabit the sea on opposite sides of the

isthmus of Panama are wholly distinct;[Footnote: Recent investigations tend

to show that this statement is not strictly accurate.--1870.] the animals

and plants which inhabit islands are commonly distinct from those of the

neighbouring mainlands, and yet have a similarity of aspect. The mammals of

the latest tertiary epoch in the Old and New Worlds belong to the same

genera, or family groups, as those which now inhabit the same great

geographical area. The crocodilian reptiles which existed in the earliest

secondary epoch were similar in general structure to those now living, but

exhibit slight differences in their vertebræ, nasal passages, and one or

two other points. The guinea-pig has teeth which are shed before it is

born, and hence can never subserve the masticatory purpose for which they

seem contrived, and, in like manner, the female dugong has tusks which

never cut the gum. All the members of the same great group run through

similar conditions in their development, and all their parts, in the adult

state, are arranged according to the same plan. Man is more like a gorilla

than a gorilla is like a lemur. Such are a few, taken at random, among the

multitudes of similar facts which modern research has established; but when

the student seeks for an explanation of them from the supporters of the

received hypothesis of the origin of species, the reply he receives is, in

substance, of Oriental simplicity and brevity--"Mashallah! it so pleases

God!" There are different species on opposite sides of the isthmus of

Panama, because they were created different on the two sides. The pliocene

mammals are like the existing ones, because such was the plan of creation;

and we find rudimental organs and similarity of plan, because it has

pleased the Creator to set before Himself a "divine exemplar or archetype,"

and to copy it in His works; and somewhat ill, those who hold this view

imply, in some of them. That such verbal hocus-pocus should be received as

science will one day be regarded as evidence of the low state of

intelligence in the nineteenth century, just as we amuse ourselves with the

phraseology about Nature's abhorrence of a vacuum, wherewith Torricellis

compatriots were satisfied to explain the rise of water in a pump. And be

it recollected that this sort of satisfaction works not only negative but

positive ill, by discouraging inquiry, and so depriving man of the usufruct

of one of the most fertile fields of his great patrimony, Nature.

The objections to the doctrine of the origin of species by special creation

which have been detailed, must have occurred, with more or less force, to

the mind of every one who has seriously and independently considered the

subject. It is therefore no wonder that, from time to time, this hypothesis

should have been met by counter hypotheses, all as well, and some better

founded than itself; and it is curious to remark that the inventors of the

opposing views seem to have been led into them as much by their knowledge

of geology, as by their acquaintance with biology. In fact, when the mind

has once admitted the conception of the gradual production of the present

physical state of our globe, by natural causes operating through long ages

of time, it will be little disposed to allow that living beings have made

their appearance in another way, and the speculations of De Maillet and his

successors are the natural complement of Scilla's demonstration of the true

nature of fossils.

A contemporary of Newton and of Leibnitz, sharing therefore in the

intellectual activity of the remarkable age which witnessed the birth of

modern physical science, Benoît de Maillet spent a long life as a consular

agent of the French Government in various Mediterranean ports. For sixteen

years, in fact, he held the office of Consul-General in Egypt, and the

wonderful phenomena offered by the valley of the Nile appear to have

strongly impressed his mind, to have directed his attention to all facts of

a similar order which came within his observation, and to have led him to

speculate on the origin of the present condition of our globe and of its

inhabitants. But, with all his ardour for science, De Maillet seems to have

hesitated to publish views which, notwithstanding the ingenious attempts to

reconcile them with the Hebrew hypothesis contained in the preface to

"Telliamed," were hardly likely to be received with favour by his

contemporaries.

But a short time had elapsed since more than one of the great anatomists

and physicists of the Italian school had paid dearly for their endeavours

to dissipate some of the prevalent errors; and their illustrious pupil,

Harvey, the founder of modern physiology, had not fared so well, in a

country less oppressed by the benumbing influences of theology, as to tempt

any man to follow his example. Probably not uninfluenced by these

considerations, his Catholic majesty's Consul-General for Egypt kept his

theories to himself throughout a long life, for "Telliamed," the only

scientific work which is known to have proceeded from his pen, was not

printed till 1735, when its author had reached the ripe age of

seventy-nine; and though De Maillet lived three years longer, his book was

not given to the world before 1748. Even then it was anonymous to those who

were not in the secret of the anagrammatic character of its title; and the

preface and dedication are so worded as, in case of necessity, to give the

printer a fair chance of falling back on the excuse that the work was

intended for a mere _jeu d'esprit_.

The speculations of the suppositious Indian sage, though quite as sound as

those of many a "Mosaic Geology," which sells exceedingly well, have no

great value if we consider them by the light of modern science. The waters

are supposed to have originally covered the whole globe; to have deposited

the rocky masses which compose its mountains by processes comparable to

those which are now forming mud, sand, and shingle; and then to have

gradually lowered their level, leaving the spoils of their animal and

vegetable inhabitants embedded in the strata. As the dry land appeared,

certain of the aquatic animals are supposed to have taken to it, and to

have become gradually adapted to terrestrial and aërial modes of existence.

But if we regard the general tenor and style of the reasoning in relation

to the state of knowledge of the day, two circumstances appear very well

worthy of remark. The first, that De Maillet had a notion of the

modifiability of living forms (though without any precise information on

the subject), and how such modifiability might account for the origin of

species; the second, that he very clearly apprehended the great modern

geological doctrine, so strongly insisted upon by Hutton, and so ably and

comprehensively expounded by Lyell, that we must look to existing causes

for the explanation of past geological events. Indeed, the following

passage of the preface, in which De Maillet is supposed to speak of the

Indian philosopher Telliamed, his _alter ego,_ might have been written

by the most philosophical uniformitarian of the present day:--

"Ce qu'il y a d'étonnant, est que pour arriver à ces connaissances il

semble avoir perverti l'ordre naturel, puisqu'au lieu de s'attacher d'abord

à rechercher l'origine de notre globe il a commence par travailler à

s'instruire de la nature. Mais à l'entendre, ce renversement de l'ordre a

été pour lui l'effet d'un génie favorable qui l'a conduit pas à pas et

comme par la main aux découvertes les plus sublimes. C'est en décomposant

la substance de ce globe par tine anatomie exacte de toutes ses parties

qu'il a premierement appris de quelles matières il était composé et quels

arrangemens ces mêmes matières observaient entre elles. Ces lumieres

jointes à l'esprit de comparaison toujours nécessaire à quiconque

entreprend de percer les voiles dont la nature aime à se cacher, ont servi

de guide à notre philosophe pour parvenir à des connoissances plus

intéressantes. Par la matière et l'arrangement de ces compositions il

prétend avoir reconnu quelle est la véritable origine de ce globe que nous

habitons, comment et par qui il a été formé."-Pp. xix. xx.

But De Maillet was before his age, and as could hardly fail to happen to

one who speculated on a zoological and botanical question before Linnæus,

and on a physiological problem before Haller, he fell into great errors

here and there; and hence, perhaps, the general neglect of his work.

Robinet's speculations are rather behind, than in advance of, those of De

Maillet; and though Linnæus may have played with the hypothesis of

transmutation, it obtained no serious support until Lamarck adopted it, and

advocated it with great ability in his "Philosophie Zoologique."

Impelled towards the hypothesis of the transmutation of species, partly by

his general cosmological and geological views; partly by the conception of

a graduated, though irregularly branching, scale of being, which had arisen

out of his profound study of plants and of the lower forms of animal life,

Lamarck, whose general line of thought often closely resembles that of De

Maillet, made a great advance upon the crude and merely speculative manner

in which that writer deals with the question of the origin of living

beings, by endeavouring to find physical causes competent to effect that

change of one species into another, which De Maillet had only supposed to

occur. And Lamarck conceived that he had found in Nature such causes, amply

sufficient for the purpose in view. It is a physiological fact, he says,

that organs are increased in size by action, atrophied by inaction; it is

another physiological fact that modifications produced are transmissible to

offspring. Change the actions of an animal, therefore, and you will change

its structure, by increasing the development of the parts newly brought

into use and by the diminution of those less used; but by altering the

circumstances which surround it you will alter its actions, and hence, in

the long run, change of circumstance must produce change of organisation.

All the species of animals, therefore, are, in Lamarck's view, the result

of the indirect action of changes of circumstance, upon those primitive

germs which he considered to have originally arisen, by spontaneous

generation, within the waters of the globe. It is curious, however, that

Lamarck should insist so strongly [Footnote: See _Phil. Zoologique_,

vol. i. p. 222. et seq.] as he has done, that circumstances never in any

degree directly modify the form or the organisation of animals, but only

operate by changing their wants and consequently their actions; for he

thereby brings upon himself the obvious question, How, then, do plants,

which cannot be said to have wants or actions, become modified? To this he

replies, that they are modified by the changes in their nutritive

processes, which are effected by changing circumstances; and it does not

seem to have occurred to him that such changes might be as well supposed to

take place among animals.

When we have said that Lamarck felt that mere speculation was not the way

to arrive at the origin of species, but that it was necessary, in order to

the establishment of any sound theory on the subject, to discover by

observation or otherwise, some _vera causa_, competent to give rise to

them; that he affirmed the true order of classification to coincide with

the order of their development one from another; that he insisted on the

necessity of allowing sufficient time, very strongly; and that all the

varieties of instinct and reason were traced back by him to the same cause

as that which has given rise to species, we have enumerated his chief

contributions to the advance of the question. On the other hand, from his

ignorance of any power in Nature competent to modify the structure of

animals, except the development of parts, or atrophy of them, in

consequence of a change of needs, Lamarck was led to attach infinitely

greater weight than it deserves to this agency, and the absurdities into

which he was led have met with deserved condemnation. Of the struggle for

existence, on which, as we shall see, Mr. Darwin lays such great stress, he

had no conception; indeed, he doubts whether there really are such things

as extinct species, unless they be such large animals as may have met their

death at the hands of man; and so little does he dream of there being any

other destructive causes at work, that, in discussing the possible

existence of fossil shells, he asks, "Pourquoi d'ailleurs seroient-ils

perdues dès que l'homme n'a pu opérer leur destruction?" ("Phil. Zool.,"

vol. i. p. 77.) Of the influence of selection Lamarck has as little notion,

and he makes no use of the wonderful phenomena which are exhibited by

domesticated animals, and illustrate its powers. The vast influence of

Cuvier was employed against the Lamarckian views, and, as the untenability

of some of his conclusions was easily shown, his doctrines sank under the

opprobrium of scientific, as well as of theological, heterodoxy. Nor have

the efforts made of late years to revive them tended to re-establish their

credit in the minds of sound thinkers acquainted with the facts of the

case; indeed it may be doubted whether Lamarck has not suffered more from

his friends than from his foes.

Two years ago, in fact, though we venture to question if even the strongest

supporters of the special creation hypothesis had not, now and then, an

uneasy consciousness that all was not right, their position seemed more

impregnable than ever, if not by its own inherent strength, at any rate by

the obvious failure of all the attempts which had been made to carry it. On

the other hand, however much the few, who thought deeply on the question of

species, might be repelled by the generally received dogmas, they saw no

way of escaping from them save by the adoption of suppositions so little

justified by experiment or by observation as to be at least equally

distasteful.

The choice lay between two absurdities and a middle condition of uneasy

scepticism; which last, however unpleasant and unsatisfactory, was

obviously the only justifiable state of mind under the circumstances.

Such being the general ferment in the minds of naturalists, it is no wonder

that they mustered strong in the rooms of the Linnæan Society, on the 1st

of July of the year 1858, to hear two papers by authors living on opposite

sides of the globe, working out their results independently, and yet

professing to have discovered one and the same solution of all the problems

connected with species. The one of these authors was an able naturalist,

Mr. Wallace, who had been employed for some years in studying the

productions of the islands of the Indian Archipelago, and who had forwarded

a memoir embodying his views to Mr. Darwin, for communication to the

Linnæan Society. On perusing the essay, Mr. Darwin was not a little

surprised to find that it embodied some of the leading ideas of a great

work which he had been preparing for twenty years, and parts of which,

containing a development of the very same views, had been perused by his

private friends fifteen or sixteen years before. Perplexed in what manner

to do full justice both to his friend and to himself, Mr. Darwin placed the

matter in the hands of Dr. Hooker and Sir Charles Lyell, by whose advice he

communicated a brief abstract of his own views to the Linnæan Society, at

the same time that Mr. Wallace's paper was read. Of that abstract, the work

on the "Origin of Species" is an enlargement; but a complete statement of

Mr. Darwin's doctrine is looked for in the large and well-illustrated work

which he is said to be preparing for publication.

The Darwinian hypothesis has the merit of being eminently simple and

comprehensible in principle, and its essential positions may be stated in a

very few words: all species have been produced by the development of

varieties from common stocks; by the conversion of these, first into

permanent races and then into new species, by the process of _natural

selection_, which process is essentially identical with that artificial

selection by which man has originated the races of domestic animals--the

_struggle for existence_ taking the place of man, and exerting, in the

case of natural selection, that selective action which he performs in

artificial selection.

The evidence brought forward by Mr. Darwin in support of his hypothesis is

of three kinds. First, he endeavours to prove that species may be

originated by selection; secondly, he attempts to show that natural causes

are competent to exert selection; and thirdly, he tries to prove that the

most remarkable and apparently anomalous phænomena exhibited by the

distribution, development, and mutual relations of species, can be shown to

be deducible from the general doctrine of their origin, which he propounds,

combined with the known facts of geological change; and that, even if all

these phænomena are not at present explicable by it, none are necessarily

inconsistent with it.

There cannot be a doubt that the method of inquiry which Mr. Darwin has

adopted is not only rigorously in accordance with the canons of scientific

logic, but that it is the only adequate method. Critics exclusively trained

in classics or in mathematics, who have never determined a scientific fact

in their lives by induction from experiment or observation, prate learnedly

about Mr. Darwin's method, which is not inductive enough, not Baconian

enough, forsooth, for them. But even if practical acquaintance with the

process of scientific investigation is denied them, they may learn, by the

perusal of Mr. Mill's admirable chapter "On the Deductive Method," that

there are multitudes of scientific inquiries in which the method of pure

induction helps the investigator but a very little way.

"The mode of investigation," says Mr. Mill, "which, from the proved

inapplicability of direct methods of observation and experiment, remains to

us as the main source of the knowledge we possess, or can acquire,

respecting the conditions and laws of recurrence of the more complex

phænomena, is called, in its most general expression, the deductive method,

and consists of three operations: the first, one of direct induction; the

second, of ratiocination; and the third, of verification."

Now, the conditions which have determined the existence of species are not

only exceedingly complex, but, so far as the great majority of them are

concerned, are necessarily beyond our cognisance. But what Mr. Darwin has

attempted to do is in exact accordance with the rule laid down by Mr. Mill;

he has endeavoured to determine certain great facts inductively, by

observation and experiment; he has then reasoned from the data thus

furnished; and lastly, he has tested the validity of his ratiocination by

comparing his deductions with the observed facts of Nature. Inductively,

Mr. Darwin endeavours to prove that species arise in a given way.

Deductively, he desires to show that, if they arise in that way, the facts

of distribution, development, classification, &c., may be accounted for,

_i.e._ may be deduced from their mode of origin, combined with

admitted changes in physical geography and climate, during an indefinite

period. And this explanation, or coincidence of observed with deduced

facts, is, so far as it extends, a verification of the Darwinian view.

There is no fault to be found with Mr. Darwin's method, then; but it is

another question whether he has fulfilled all the conditions imposed by

that method. Is it satisfactorily proved, in fact, that species may be

originated by selection? that there is such a thing as natural selection?

that none of the phænomena exhibited by species are inconsistent with the

origin of species in this way? If these questions can be answered in the

affirmative, Mr. Darwin's view steps out of the rank of hypotheses into

those of proved theories; but, so long as the evidence at present adduced

falls short of enforcing that affirmation, so long, to our minds, must the

new doctrine be content to remain among the former--an extremely valuable,

and in the highest degree probable, doctrine, indeed the only extant

hypothesis which is worth anything in a scientific point of view; but still

a hypothesis, and not yet the theory of species.

After much consideration, and with assuredly no bias against Mr. Darwin's

views, it is our clear conviction that, as the evidence stands, it is not

absolutely proven that a group of animals, having all the characters

exhibited by species in Nature, has ever been originated by selection,

whether artificial or natural. Groups having the morphological character of

species--distinct and permanent races in fact--have been so produced over

and over again; but there is no positive evidence, at present, that any

group of animals has, by variation and selective breeding, given rise to

another group which was, even in the least degree, infertile with the

first. Mr. Darwin is perfectly aware of this weak point, and brings forward

a multitude of ingenious and important arguments to diminish the force of

the objection. We admit the value of these arguments to their fullest

extent; nay, we will go so far as to express our belief that experiments,

conducted by a skilful physiologist, would very probably obtain the desired

production of mutually more or less infertile breeds from a common stock,

in a comparatively few years; but still, as the case stands at present,

this "little rift within the lute" is not to be disguised nor overlooked.

In the remainder of Mr. Darwin's argument our own private ingenuity has not

hitherto enabled us to pick holes of any great importance; and judging by

what we hear and read, other adventurers in the same field do not seem to

have been much more fortunate. It has been urged, for instance, that in his

chapters on the struggle for existence and on natural selection, Mr. Darwin

does not so much prove that natural selection does occur, as that it must

occur; but, in fact, no other sort of demonstration is attainable. A race

does not attract our attention in Nature until it has, in all probability,

existed for a considerable time, and then it is too late to inquire into

the conditions of its origin. Again, it is said that there is no real

analogy between the selection which takes place under domestication, by

human influence, and any operation which can be effected by Nature, for man

interferes intelligently. Reduced to its elements, this argument implies

that an effect produced with trouble by an intelligent agent must, _à

fortiori,_ be more troublesome, if not impossible, to an unintelligent

agent. Even putting aside the question whether Nature, acting as she does

according to definite and invariable laws, can be rightly called an

unintelligent agent, such a position as this is wholly untenable. Mix salt

and sand, and it shall puzzle the wisest of men, with his mere natural

appliances, to separate all the grains of sand from all the grains of salt;

but a shower of rain will effect the same object in ten minutes. And so,

while man may find it tax all his intelligence to separate any variety

which arises, and to breed selectively from it, the destructive agencies

incessantly at work in Nature, if they find one variety to be more soluble

in circumstances than the other, will inevitably, in the long run,

eliminate it.

A frequent and a just objection to the Lamarckian hypothesis of the

transmutation of species is based upon the absence of transitional forms

between many species. But against the Darwinian hypothesis this argument

has no force. Indeed, one of the most valuable and suggestive parts of Mr.

Darwin's work is that in which he proves, that the frequent absence of

transitions is a necessary consequence of his doctrine, and that the stock

whence two or more species have sprung, need in no respect be intermediate

between these species. If any two species have arisen from a common stock

in the same way as the carrier and the pouter, say, have arisen from the

rock-pigeon, then the common stock of these two species need be no more

intermediate between the two than the rock-pigeon is between the carrier

and pouter. Clearly appreciate the force of this analogy, and all the

arguments against the origin of species by selection, based on the absence

of transitional forms, fall to the ground. And Mr. Darwin's position might,

we think, have been even stronger than it is if he had not embarrassed

himself with the aphorism, "_Natura non facit saltum_," which turns up

so often in his pages. We believe, as we have said above, that Nature does

make jumps now and then, and a recognition of the fact is of no small

importance in disposing of many minor objections to the doctrine of

transmutation.

But we must pause. The discussion of Mr. Darwin's arguments in detail would

lead us far beyond the limits within which we proposed, at starting, to

confine this article. Our object has been attained if we have given an

intelligible, however brief, account of the established facts connected

with species, and of the relation of the explanation of those facts offered

by Mr. Darwin to the theoretical views held by his predecessors and his

contemporaries, and, above all, to the requirements of scientific logic. We

have ventured to point out that it does not, as yet, satisfy all those

requirements; but we do not hesitate to assert that it is as superior to

any preceding or contemporary hypothesis, in the extent of observational

and experimental basis on which it rests, in its rigorously scientific

method, and in its power of explaining biological phenomena, as was the

hypothesis of Copernicus to the speculations of Ptolemy. But the planetary

orbits turned out to be not quite circular after all, and, grand as was the

service Copernicus rendered to science, Kepler and Newton had to come after

him. What if the orbit of Darwinism should be a little too circular? What

if species should offer residual phænomena, here and there, not explicable

by natural selection? Twenty years hence naturalists may be in a position

to say whether this is, or is not, the case; but in either event they will

owe the author of "The Origin of Species" an immense debt of gratitude. We

should leave a very wrong impression on the reader's mind if we permitted

him to suppose that the value of that work depends wholly on the ultimate

justification of the theoretical views which it contains. On the contrary,

if they were disproved to-morrow, the book would still be the best of its

kind--the most compendious statement of well-sifted facts bearing on the

doctrine of species that has ever appeared. The chapters on Variation, on

the Struggle for Existence, on Instinct, on Hybridism, on the Imperfection

of the Geological Record, on Geographical Distribution, have not only no

equals, but, so far as our knowledge goes, no competitors, within the range

of biological literature. And viewed as a whole, we do not believe that,

since the publication of Von Baer's "Researches on Development," thirty

years ago, any work has appeared calculated to exert so large an influence,

not only on the future of Biology, but in extending the domination of

Science over regions of thought into which she has, as yet, hardly

penetrated.