DARWIN ON THE ORIGIN OF SPECIES.

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wholly superseded the ambition and the vanity of the carnal man within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 savans, 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, or 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 supposition

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 few, even of 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. Mammæ; 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 palæontologists, 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,[62] "that few naturalists

now-a-days, 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 in 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 exuvia; 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 these 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 a 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. 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 and yet so steady and purpose-like 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 phenomena of vitality are not something apart from other

physical phenomena, 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 whose members 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 éclorre 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 moveable 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 the 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, 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 pre-potent 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 toes, like their mother, though the

hands and feet of George were slightly deformed; the last, a girl, had

five fingers and 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 husbands, 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 instal 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.[63] 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 whose skeleton 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 grandchildren 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 form, 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 whose transmission 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 Sequard,

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.

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 ones _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 vertebræ, 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 a 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

phenomena of hybridization--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 also 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 even breed 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 ensuring 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 superadded

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 hybridization 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_, whose male element will

fertilize 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 organization

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, whose members 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

phenomena 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 phenomena of hybridization 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 phenomena 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 civilized 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 harmonize 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 dogmatism 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 forms of matter 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 the older tertiaries; the Maestricht beds linking

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

abundant fauna of mixed mesozoic and paleozoic 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 this 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 phenomena 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 skimmers 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; 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 Torricelli's 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 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" (and which we

recommend for Mr. MacCausland's perusal), 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 supposititious 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 up 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 the 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 aerial 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. The following passage of the

preface indeed, 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

connoissances il semble avoir perverti l'ordre naturel,

puisqu'au lieu de s'attacher d'abord à rechercher

l'origine de notre globe il a commencé 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 une anatomie exacte de

toutes ses parties qu'il a premièrement appris de quelles

matières il était composé et quels arrangemens ces mêmes

matières observaient entre elles. Ces lumières 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 organization. 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[64] as he has done,

that circumstances never in any degree directly modify the form or the

organization 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 first 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.[65]

* * * * *

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 phenomena 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 not all these phenomena are 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

phenomena, 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 phenomena 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

ranks 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 phenomena 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.