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Review of] The Origin of Species by Mean of Natural

Selection

by Asa Gray (1860)

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[Review of] The Origin of Species by Mean of Natural Selection

by Asa Gray (1860)

First published in American Journal of Science and Arts, March, 1860

Reprinted in Gray, Asa. (1876). Darwiniana: Essays and Reviews Pertaining to Darwinism. .

Posted June 2004

This book is already exciting much attention. Two American editions are announced, through

which it will become familiar to many of our readers, before these pages are issued. An

abstract of the argument -- for "the whole volume is one long argument," as the author states --

is unnecessary in such a case; and it would be difficult to give by detached extracts. For the

volume itself is an abstract, a prodromus of a detailed work upon which the author has been

laboring for twenty years, and which "will take two or three more years to complete." It is

exceedingly compact; and although useful summaries are appended to the several chapters,

and a general recapitulation contains the essence of the whole, yet much of the aroma escapes

in the treble distillation, or is so concentrated that the flavor is lost to the general or even to the

scientific reader. The volume itself -- the proof-spirit -- is just condensed enough for its purpose.

It will be far more widely read, and perhaps will make deeper impression, than the elaborate

work might have done, with all its full details of the facts upon which the author's sweeping

conclusions have been grounded. At least it is a more readable book: but all the facts that can

be mustered in favor of the theory are still likely to be needed.

Who, upon a single perusal, shall pass judgment upon a work like this, to which twenty of the

best years of the life of a most able naturalist have been devoted? And who among those

naturalists who hold a position that entitles them to pronounce summarily upon the subject, can

be expected to divest himself for the nonce of the influence of received and favorite systems?

In fact, the controversy now opened is not likely to be settled in an off-hand way, nor is it

desirable that it should be. A spirited conflict among opinions of every grade must ensue, which

-- to borrow an illustration from the doctrine of the book before us -- may be likened to the

conflict in Nature among races in the struggle for life, which Mr. Darwin describes; through

which the views most favored by facts will be developed and tested by "Natural Selection," the

weaker ones be destroyed in the process, and the strongest in the long-run alone survive.

The duty of reviewing this volume in the American Journal of Science would naturally devolve

upon the principal editor,' whose wide observation and profound knowledge of various

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departments of natural history, as well as of geology, particularly qualify him for the task. But he

has been obliged to lay aside his pen, and to seek in distant lands the entire repose from

scientific labor so essential to the restoration of his health -- a consummation devoutly to be

wished, and confidently to be expected. Interested as Mr. Dana would be in this volume, he

could not be expected to accept this doctrine.

Views so idealistic as those upon which his "Thoughts upon Species" [I-2] are grounded, will

not harmonize readily with a doctrine so thoroughly naturalistic as that of Mr. Darwin. Though it

is just possible that one who regards the kinds of elementary matter, such as oxygen and

hydrogen, and the definite compounds of these elementary matters, and their compounds

again, in the mineral kingdom, as constituting species, in the same sense, fundamentally, as

that of animal and vegetable species, might admit an evolution of one species from another in

the latter as well as the former case.

Between the doctrines of this volume and those of the other great naturalist whose name

adorns the title-page of this journal, the widest divergence appears. It is interesting to contrast

the two, and, indeed, is necessary to our purpose; for this contrast brings out most prominently,

and sets in strongest light and shade, the main features of the theory of the origination of

species by means of Natural Selection.

The ordinary and generally-received view assumes the independent, specific creation of each

kind of plant and animal in a primitive stock, which reproduces its like from generation to

generation, and so continues the species. Taking the idea of species from this perennial

succession of essentially similar individuals, the chain is logically traceable back to a local

origin in a single stock, a single pair, or a single individual, from which all the individuals

composing the species have proceeded by natural generation. Although the similarity of

progeny to parent is fundamental in the conception of species, yet the likeness is by no means

absolute; all species vary more or less, and some vary remarkably -- partly from the influence

of altered circumstances, and partly (and more really) from unknown constitutional causes

which altered conditions favor rather than originate. But these variations are supposed to be

mere oscillations from a normal state, and in Nature to be limited if not transitory; so that the

primordial differences between species and species at their beginning have not been effaced,

nor largely obscured, by blending through variation. Consequently, whenever two reputed

species are found to blend in Nature through a series of intermediate forms, community of

origin is inferred, and all the forms, however diverse, are held to belong to one species.

Moreover, since bisexuality is the rule in Nature (which is practically carried out, in the long-run,

far more generally than has been suspected), and the heritable qualities of two distinct

individuals are mingled in the offspring, it is supposed that the general sterility of hybrid

progeny interposes an effectual barrier against the blending of the original species by crossing.

From this generally-accepted view the well-known theory of and the recent one of diverge in

exactly opposite directions.

That of Agassiz differs fundamentally from the ordinary view only in this, that it discards the

idea of a common descent as the real bond of union among the individuals of a species, and

also the idea of a local origin -- supposing, instead, that each species originated

simultaneously, generally speaking, over the whole geographical area it now occupies or has

occupied, and in perhaps as many individuals as it numbered at any subsequent period.

Mr. Darwin, on the other hand, holds the orthodox view of the descent of all the individuals of a

species not only from a local birthplace, but from a single ancestor or pair; and that each

species has extended and established itself, through natural agencies, wherever it could; so

that the actual geographical distribution of any species is by no means a primordial

arrangement, but a natural result. He goes farther, and this volume is a protracted argument

intended to prove that the species we recognize have not been independently created, as such,

but have descended, like varieties, from other species. Varieties, on this view, are incipient or

possible species: species are varieties of a larger growth and a wider and earlier divergence

from the parent stock; the difference is one of degree, not of kind.

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The ordinary view -- rendering unto Caesar the things that are Caesar's -- looks to natural

agencies for the actual distribution and perpetuation of species, to a supernatural for their

origin.

The theory of regards the origin of species and their present general distribution over the world

as equally primordial, equally supernatural; that of , as equally derivative, equally natural.

The theory of Agassiz, referring as it does the phenomena both of origin and distribution directly

to the Divine will -- thus removing the latter with the former out of the domain of inductive

science (in which efficient cause is not the first, but the last word) -- may be said to be theistic

to excess. The contrasted theory is not open to this objection. Studying the facts and

phenomena in reference to proximate causes, and endeavoring to trace back the series of

cause and effect as far as possible, Darwin's aim and processes are strictly scientific, and his

endeavor, whether successful or futile, must be regarded as a legitimate attempt to extend the

domain of natural or physical science. For, though it well may be that "organic forms have no

physical or secondary cause," yet this can be proved only indirectly, by the failure of every

attempt to refer the phenomena in question to causal laws. But, however originated, and

whatever be thought of Mr. Darwin's arduous undertaking in this respect, it is certain that plants

and animals are subject from their birth to physical influences, to which they have to

accommodate themselves as they can. How literally they are "born to trouble," and how

incessant and severe the struggle for life generally is, the present volume graphically describes.

Few will deny that such influences must have gravely affected the range and the association of

individuals and species on the earth's surface. Mr. Darwin thinks that, acting upon an inherent

predisposition to vary, they have sufficed even to modify the species themselves and produce

the present diversity. Mr. Agassiz believes that they have not even affected the geographical

range and the actual association of species, still less their forms; but that every adaptation of

species to climate, and of species to species, is as aboriginal, and therefore as inexplicable, as

are the organic forms themselves.

Who shall decide between such extreme views so ably maintained on either hand, and say how

much of truth there may be in each? The present reviewer has not the presumption to

undertake such a task. Having no prepossession in favor of naturalistic theories, but struck with

the eminent ability of Mr. Darwin's work, and charmed with its fairness, our humbler duty will be

performed if, laying aside prejudice as much as we can, we shall succeed in giving a fair

account of its method and argument, offering by the way a few suggestions, such as might

occur to any naturalist of an inquiring mind. An editorial character for this article must in justice

be disclaimed. The plural pronoun is employed not to give editorial weight, but to avoid even

the appearance of egotism, and also the circumlocution which attends a rigorous adherence to

the impersonal style.

We have contrasted these two extremely divergent theories, in their broad statements. It must

not be inferred that they have no points nor ultimate results in common.

In the first place, they practically agree in upsetting, each in its own way, the generally-received

definition of species, and in sweeping away the ground of their objective existence in Nature.

The orthodox conception of species is that of lineal descent: all the descendants of a common

parent, and no other, constitute a species; they have a certain identity because of their descent,

by which they are supposed to be recognizable. So naturalists had a distinct idea of what they

meant by the term species, and a practical rule, which was hardly the less useful because

difficult to apply in many cases, and because its application was indirect: that is, the community

of origin had to be inferred from the likeness; such degree of similarity, and such only, being

held to be con-specific as could be shown or reasonably inferred to be compatible with a

common origin. And the usual concurrence of the whole body of naturalists (having the same

data before them) as to what forms are species attests the value of the rule, and also indicates

some real foundation for it in Nature. But if species were created in numberless individuals over

broad spaces of territory, these individuals are connected only in idea, and species differ from

varieties on the one hand, and from genera, tribes, etc., on the other, only in degree; and no

obvious natural reason remains for fixing upon this or that degree as specific, at least no

natural standard, by which the opinions of different naturalists may be correlated. Species upon

this view are enduring, but subjective and ideal. Any three or more of the human races, for

example, are species or not species, according to the bent of the naturalist's mind. Darwin's

theory brings us the other way to the same result. In his view, not only all the individuals of a

species are descendants of a common parent, but of all the related species also. Affinity,

relationship, all the terms which naturalists use figuratively to express an underived,

unexplained resemblance among species, have a literal meaning upon Darwin's system, which

they little suspected, namely, that of inheritance. Varieties are the latest offshoots of the

genealogical tree in "an unlineal" order; species, those of an earlier date, but of no definite

distinction; genera, more ancient species, and so on. The human races, upon this view,

likewise may or may not be species according to the notions of each naturalist as to what

differences are specific; but, if not species already, those races that last long enough are sure

to become so. It is only a question of time.

How well the simile of a genealogical tree illustrates the main ideas of Darwin's theory the

following extract from the summary of the fourth chapter shows:

"It is a truly wonderful fact -- the wonder of which we are apt to overlook from familiarity -- that

all animals and all plants throughout all time and space should be related to each other in

group subordinate to group, in the manner which we everywhere behold -- namely, varieties of

the same species most closely related together, species of the same genus less closely and

unequally related together, forming sections and sub-genera, species of distinct genera much

less closely related, and genera related in different degrees, forming sub-families, families,

orders, sub-classes, and classes. The several subordinate groups in any class cannot be

ranked in a single file, but seem rather to be clustered round points, and these round other

points, and so on in almost endless cycles. On the view that each species has been

independently created, I can see no explanation of this great fact in the classification of all

organic beings; but, to the best of my judgment, it is explained through inheritance and the

complex action of natural selection, entailing extinction and divergence of character, as we

have seen illustrated in the diagram.

"The affinities of all the beings of the same class have sometimes been represented by a great

tree. I believe this simile largely speaks the truth. The green and budding twigs may represent

existing species; and those produced during each former year may represent the long

succession of extinct species. At each period of growth all the growing twigs have tried to

branch out on all sides, and overtop and kill the surrounding twigs and branches, in the same

manner as species and groups of species have tried to overmaster other species in the great

battle for life. The limbs divided into great branches, and these into lesser and lesser branches,

were themselves once, when the tree was small, budding twigs; and this connection of the

former and present buds by ramifying branches may well represent the classification of all

extinct and living species in groups subordinate to groups. Of the many twigs which flourished

when the tree was a mere bush, only two or three, now grown into great branches, yet survive

and bear all the other branches; so with the species which lived during long-past geological

periods, very few now have living and modified descendants. From the first growth of the tree,

many a limb and branch has decayed and dropped off; and these lost branches of various sizes

may represent those whole orders, families, and genera, which have now no living

representatives, and which are known to us only from having been found in a fossil state. As we

here and there see a thin, straggling branch springing from a fork low down in a tree, and which

by some chance has been favored and is still alive on its summit, so we occasionally see an

animal like the Ornithorhynchus or Lepidosiren, which in some small degree connects by its

affinities two large branches of life, and which has apparently been saved from fatal competition

by having inhabited a protected station. As buds give rise by growth to fresh buds, and these, if

vigorous, branch out and overtop on all sides many a feebler branch, so by generation I believe

it has been with the great Tree of Life, which fills with its dead and broken branches the crust of

the earth, and covers the surface with its ever-branching and beautiful ramification."

It may also be noted that there is a significant correspondence between the rival theories as to

the main facts employed. Apparently every capital fact in the one view is a capital fact in the

other. The difference is in the interpretation. To run the parallel ready made to our hands: [I-4]

"The simultaneous existence of the most diversified types under identical circumstances ... the

repetition of similar types under the most diversified circumstances ... the unity of plan in

otherwise highly-diversified types of animals ... the correspondence, now generally known as

special homologies, in the details of structure otherwise entirely disconnected, down to the

most minute peculiarities ... the various degrees and different kinds of relationship among

animals which (apparently) can have no genealogical connection ... the simultaneous existence

in the earliest geological periods, ... of representatives of all the great types of the animal

kingdom ... the gradation based upon complications of structure which may be traced among

animals built upon the same plan; the distribution of some types over the most extensive range

of surface of the globe, while others are limited to particular geographical areas ... the identity

of structures of these types, notwithstanding their wide geographical distribution ... the

community of structure in certain respects of animals otherwise entirely different, but living

within the same geographical area ... the connection by series of special structures observed in

animals widely scattered over the surface of the globe ... the definite relations in which animals

stand to the surrounding world, ... the relations in which individuals of the same species stand

to one another ... the limitation of the range of changes which animals undergo during their

growth ... the return to a definite norm of animals which multiply in various ways ... the order of

succession of the different types of animals and plants characteristic of the different geological

epochs, ... the localization of some types of animals upon the same points of the surface of the

globe during several successive geological periods ... the parallelism between the order of

succession of animals and plants in geological times, and the gradation among their living

representatives ... the parallelism between the order of succession of animals in geological

times and the changes their living representatives undergo during their embryological growth,

[I-5] ... the combination in many extinct types of characters which in later ages appear

disconnected in different types, ... the parallelism between the gradation among animals and

the changes they undergo during their growth, ... the relations existing between these different

series and the geographical distribution of animals, ... the connection of all the known features

of Nature into one system -- "

In a word, the whole relations of animals, etc., to surrounding Nature and to each other, are

regarded under the one view as ultimate facts, or in the ultimate aspect, and interpreted

theologically; under the other as complex facts, to be analyzed and interpreted scientifically.

The one naturalist, perhaps too largely assuming the scientifically unexplained to be

inexplicable, views the phenomena only in their supposed relation to the Divine mind. The

other, naturally expecting many of these phenomena to be resolvable under investigation,

views them in their relations to one another, and endeavors to explain them as far as he can

(and perhaps farther) through natural causes.

But does the one really exclude the other? Does the investigation of physical causes stand

opposed to the theological view and the study of the harmonies between mind and Nature?

More than this, is it not most presumable that an intellectual conception realized in Nature

would be realized through natural agencies? Mr. Agassiz answers these questions affirmatively

when he declares that "the task of science is to investigate what has been done, to inquire if

possible how it has been done, rather than to ask what is possible for the Deity, since we can

know that only by what actually exists;" and also when he extends the argument for the

intervention in Nature of a creative mind to its legitimate application in the inorganic world;

which, he remarks, "considered in the same light, would not fail also to exhibit unexpected

evidence of thought, in the character of the laws regulating the chemical combinations, the

action of physical forces, etc., etc." [I-6] Mr. Agassiz, however, pronounces that "the connection

between the facts is only intellectual" -- an opinion which the analogy of the inorganic world,

just referred to, does not confirm, for there a material connection between the facts is justly

held to be consistent with an intellectual -- and which the most analogous cases we can think of

in the organic world do not favor; for there is a material connection between the grub, the pupa,

and the butterfly, between the tadpole and the frog, or, still better, between those distinct

animals which succeed each other in alternate and very dissimilar generations. So that mere

analogy might rather suggest a natural connection than the contrary; and the contrary cannot

be demonstrated until the possibilities of Nature under the Deity are fathomed.

But, the intellectual connection being undoubted, Mr. Agassiz properly refers the whole to "the

agency of Intellect as its first cause." In doing so, however, he is not supposed to be offering a

scientific explanation of the phenomena. Evidently he is considering only the ultimate why, not

the proximate why or how.

Now the latter is just what Mr. Darwin is considering. He conceives of a physical connection

between allied species; but we suppose he does not deny their intellectual connection, as

related to a supreme intelligence. Certainly we see no reason why he should, and many

reasons why he should not, Indeed, as we contemplate the actual direction of investigation and

speculation in the physical and natural sciences, we dimly apprehend a probable synthesis of

these divergent theories, and in it the ground for a strong stand against mere naturalism. Even

if the doctrine of the origin of species through natural selection should prevail in our day, we

shall not despair; being confident that the genius of an Agassiz will be found equal to the work

of constructing, upon the mental and material foundations combined, a theory of Nature as

theistic and as scientific as that which he has so eloquently expounded.

To conceive the possibility of "the descent of species from species by insensibly fine

gradations" during a long course of time, and to demonstrate its compatibility with a strictly

theistic view of the universe, is one thing; to substantiate the theory itself or show its likelihood

is quite another thing. This brings us to consider what Darwin's theory actually is, and how he

supports it.

That the existing kinds of animals and plants, or many of them, may be derived from other and

earlier kinds, in the lapse of time, is by no means a novel proposition. Not to speak of ancient

speculations of the sort, it is the well-known Lamarckian theory. The first difficulty which such

theories meet with is that in the present age, with all its own and its inherited prejudgments, the

whole burden of proof is naturally, and indeed properly, laid upon the shoulders of the

propounders; and thus far the burden has been more than they could bear. From the very

nature of the case, substantive proof of specific creation is not attainable; but that of derivation

or transmutation of species may be. He who affirms the latter view is bound to do one or both of

two things: 1. Either to assign real and adequate causes, the natural or necessary result of

which must be to produce the present diversity of species and their actual relations; or, 2. To

show the general conformity of the whole body of facts to such assumption, and also to adduce

instances explicable by it and inexplicable by the received view, so perhaps winning our assent

to the doctrine, through its competency to harmonize all the facts, even though the cause of the

assumed variation remain as occult as that of the transformation of tadpoles into frogs, or that

of Coryne into Sarzia.

The first line of proof, successfully carried out, would establish derivation as a true physical

theory; the second, as a sufficient hypothesis.

Lamarck mainly undertook the first line, in a theory which has been so assailed by ridicule that

it rarely receives the credit for ability to which in its day it was entitled, But he assigned partly

unreal, partly insufficient causes; and the attempt to account for a progressive change in

species through the direct influence of physical agencies, and through the appetencies and

habits of animals reacting upon their structure, thus causing the production and the successive

modification of organs, is a conceded and total failure. The shadowy author of the "Vestiges of

the Natural History of Creation" can hardly be said to have undertaken either line, in a scientific

way. He would explain the whole progressive evolution of Nature by virtue of an inherent

tendency to development, thus giving us an idea or a word in place of a natural cause, a

restatement of the proposition instead of an explanation. Mr. Darwin attempts both lines of

proof, and in a strictly scientific spirit; but the stress falls mainly upon the first, for, as he does

assign real causes, he is bound to prove their adequacy.

It should be kept in mind that, while all direct proof of independent origination is attainable from

the nature of the case, the overthrow of particular schemes of derivation has not established

the opposite proposition. The futility of each hypothesis thus far proposed to account for

derivation may be made apparent, or unanswerable objections may be urged against it; and

each victory of the kind may render derivation more improbable, and therefore specific creation

more probable, without settling the question either way. New facts, or new arguments and a

new mode of viewing the question, may some day change the whole aspect of the case. It is

with the latter that Mr. Darwin now reopens the discussion.

Having conceived the idea that varieties are incipient species, he is led to study variation in the

field where it shows itself most strikingly, and affords the greatest facilities to investigation.

Thoughtful naturalists have had increasing grounds to suspect that a reexamination of the

question of species in zoology and botany, commencing with those races which man knows

most about, viz., the domesticated and cultivated races, would be likely somewhat to modify the

received idea of the entire fixity of species. This field, rich with various but unsystematized

stores of knowledge accumulated by cultivators and breeders, has been generally neglected by

naturalists, because these races are not in a state of nature; whereas they deserve particular

attention on this very account, as experiments, or the materials for experiments, ready to our

hand. In domestication we vary some of the natural conditions of a species, and thus learn

experimentally what changes are within the reach of varying conditions in Nature. We separate

and protect a favorite race against its foes or its competitors, and thus learn what it might

become if Nature ever afforded it equal opportunities. Even when, to subserve human uses, we

modify a domesticated race to the detriment of its native vigor, or to the extent of practical

monstrosity, although we secure forms which would not be originated and could not be

perpetuated in free Nature, yet we attain wider and juster views of the possible degree of

variation. We perceive that some species are more variable than others, but that no species

subjected to the experiment persistently refuses to vary; and that, when it has once begun to

vary, its varieties are not the less but the more subject to variation. "No case is on record of a

variable being ceasing to be variable under cultivation." It is fair to conclude, from the

observation of plants and animals in a wild as well as domesticated state, that the tendency to

vary is general, and even universal. Mr. Darwin does "not believe that variability is an inherent

and necessary contingency, under all circumstances, with all organic beings, as some authors

have thought." No one supposes variation could occur under all circumstances; but the facts on

the whole imply a universal tendency, ready to be manifested under favorable circumstances.

In reply to the assumption that man has chosen for domestication animals and plants having an

extraordinary inherent tendency to vary, and likewise to withstand diverse climates, it is asked:

"How could a savage possibly know, when he first tamed an animal, whether it would vary in

succeeding generations and whether it would endure other climates? Has the little variability of

the ass or Guinea-fowl, or the small power of endurance of warmth by the reindeer, or of cold

by the common camel, prevented their domestication? I cannot doubt that if other animals and

plants, equal in number to our domesticated productions, and belonging to equally diverse

classes and countries, were taken from a state of nature, and could be made to breed for an

equal number of generations under domestication, they would vary on an average as largely as

the parent species of our existing domesticated productions have varied."

As to amount of variation, there is the common remark of naturalists that the varieties of

domesticated plants or animals often differ more widely than do the individuals of distinct

species in a wild state: and even in Nature the individuals of some species are known to vary to

a degree sensibly wider than that which separates related species. In his instructive section on

the breeds of the domestic pigeon, our author remarks that "at least a score of pigeons might

be chosen which if shown to an ornithologist, and he were told that they were wild birds, would

certainly be ranked by him as well-defined species. Moreover, I do not believe that any

ornithologist would place the English carrier, the short-faced tumbler, the runt, the barb, pouter,

and fantail, in the same genus; more especially as in each of these breeds several truly-

inherited sub-breeds, or species, as he might have called them, could be shown him." That this

is not a case like that of dogs, in which probably the blood of more than one species is mingled,

Mr. Darwin proceeds to show, adducing cogent reasons for the common opinion that all have

descended from the wild rock-pigeon. Then follow some suggestive remarks:

"I have discussed the probable origin of domestic pigeons at some, yet quite insufficient,

length; because when I first kept pigeons and watched the several kinds, knowing well how true

they bred, I felt fully as much difficulty in believing that they could ever have descended from a

common parent as any naturalist could in coming to a similar conclusion in regard to many

species of finches, or other large groups of birds, in Nature. One circumstance has struck me

much; namely, that all the breeders of the various domestic animals and the cultivators of

plants, with whom I have ever conversed, or whose treatises I have read, are firmly convinced

that the several breeds to which each has attended are descended from so many aboriginally

distinct species. Ask, as I have asked, a celebrated raiser of cattle, whether his cattle might not

have descended from long-horns, and he will laugh you to scorn. I have never met a pigeon, or

poultry, or duck, or rabbit fancier, who was not fully convinced that each main breed was

descended from a distinct species. Van Mons, in his treatise on pears and apples, shows how

utterly he disbelieves that the several sorts, for instance a Ribston-pippin or Codlin-apple, could

ever have proceeded from the seeds of the same tree. Innumerable other examples could be

given. The explanation, I think, is simple: from long-continued study they arc strongly

impressed with the differences between the several races; and though they well know that each

race varies slightly, for they win their prizes by selecting such slight differences, yet they ignore

all general arguments, and refuse to sum up in their minds slight differences accumulated

during many successive generations. May not those naturalists who, knowing far less of the

laws of inheritance than does the breeder, and knowing no more than he does of the

intermediate links in the long lines of descent, yet admit that many of our domestic races have

descended from the same parents -- may they not learn a lesson of caution, when they deride

the idea of species in a state of nature being lineal descendants of other species?"

The actual causes of variation are unknown. Mr. Darwin favors the opinion of the late Mr.

Knight, the great philosopher of horticulture, that variability tinder domestication is somehow

connected with excess of food. He regards the unknown cause as acting chiefly upon the

reproductive system of the parents, which system, judging from the effect of confinement or

cultivation upon its functions, he concludes to be more susceptible than any other to the action

of changed conditions of life. The tendency to vary certainly appears to be much stronger under

domestication than in free Nature. But we are not sure that the greater variableness of

cultivated races is not mainly owing to the far greater opportunities for manifestation and

accumulation -- a view seemingly all the more favorable to Mr. Darwin's theory. The actual

amount of certain changes, such as size or abundance of fruit, size of udder, stands of course

in obvious relation to supply of food. Really, we no more know the reason why the progeny

occasionally deviates from the parent than we do why it usually resembles it. Though the laws

and conditions governing variation are known to a certain extent, those governing inheritance

are apparently inscrutable. "Perhaps," Darwin remarks, "the correct way of viewing the whole

subject would be, to look at the inheritance of every character whatever as the rule, and non-

inheritance as the anomaly." This, from general and obvious considerations, we have long been

accustomed to do. Now, as exceptional instances are expected to be capable of explanation,

while ultimate laws are not, it is quite possible that variation may be accounted for, while the

great primary law of inheritance remains a mysterious fact.

The common proposition is, that species reproduce their like; this is a sort of general inference,

only a degree closer to fact than the statement that genera reproduce their like. The true

proposition, the fact incapable of further analysis, is, that individuals reproduce their like -- that

characteristics are inheritable. So varieties, or deviations, once originated, are perpetuable, like

species. Not so likely to be perpetuated, at the outset; for the new form tends to resemble a

grandparent and a long line of similar ancestors, as well as to resemble its immediate

progenitors. Two forces which coincide in the ordinary case, where the offspring resembles its

parent, act in different directions when it does not and it is uncertain which will prevail. If the

remoter but very potent ancestral influence predominates, the variation disappears with the life

of the individual. If that of the immediate parent -- feebler no doubt, but closer -- the variety

survives in the offspring; whose progeny now has a redoubled tendency to produce its own like;

whose progeny again is almost sure to produce its like, since it is much the same whether it

takes after its mother or its grandmother.

In this way races arise, which under favorable conditions may be as hereditary as species. In

following these indications, watching opportunities, and breeding only from those individuals

which vary most in a desirable direction, man leads the course of variation as he leads a

streamlet -- apparently at will, but never against the force of gravitation -- to a long distance

from its source, and makes it more subservient to his use or fancy. He unconsciously

strengthens those variations which he prizes when he plants the seed of a favorite fruit,

preserves a favorite domestic animal, drowns the uglier kittens of a litter, and allows only the

handsomest or the best mousers to propagate. Still more, by methodical selection, in recent

times almost marvelous results have been produced in new breeds of cattle, sheep, and

poultry, and new varieties of fruit of greater and greater size or excellence.

It is said that all domestic varieties, if left to run wild, would revert to their aboriginal stocks.

Probably they would wherever various races of one species were left to commingle. At least the

abnormal or exaggerated characteristics induced by high feeding, or high cultivation and

prolonged close breeding, would promptly disappear; and the surviving stock would soon blend

into a homogeneous result (in a way presently explained), which would naturally be taken for

the original form; but we could seldom know if it were so. It is by no means certain that the

result would be the same if the races ran wild each in a separate region. Dr. Hooker doubts if

there is a true reversion in the case of plants. Mr. Darwin's observations rather favor it in the

animal kingdom. With mingled races reversion seems well made out in the case of pigeons.

The common opinion upon this subject therefore probably has some foundation, But even if we

regard varieties as oscillations around a primitive centre or type, still it appears from the

readiness with which such varieties originate that a certain amount of disturbance would carry

them beyond the influence of the primordial attraction, where they may become new centres of

variation.

Some suppose that races cannot be perpetuated indefinitely even by keeping up the conditions

under which they were fixed; but the high antiquity of several, and the actual fixity of many of

them, negative this assumption. "To assert that we could not breed our cart and race horses,

long and short horned cattle, and poultry of various breeds, for almost an infinite number of

generations, would be opposed to all experience."

Why varieties develop so readily and deviate so widely under domestication, while they are

apparently so rare or so transient in free Nature, may easily be shown. In Nature, even with

hermaphrodite plants, there is a vast amount of cross-fertilization among various individuals of

the same species. The inevitable result of this (as was long ago explained in this Journal [I-7])

is to repress variation, to keep the mass of a species comparatively homogeneous over any

area in which it abounds in individuals. Starting from a suggestion of the late Mr. Knight, now so

familiar, that close interbreeding diminishes vigor and fertility; [I-8] and perceiving that

bisexuality is ever aimed at in Nature -- being attained physiologically in numerous cases where

it is not structurally -- Mr. Darwin has worked out the subject in detail, and shown how general

is the concurrence, either habitual or occasional, of two hermaphrodite individuals in the

reproduction of their kind; and has drawn the philosophical inference that probably no organic

being self-fertilizes indefinitely; but that a cross with another individual is occasionally --

perhaps at very long intervals -- indispensable. We refer the reader to the section on the

intercrossing of individuals (pp. 96 -- 101), and also to an article in the Gardeners' Chronicle a

year and a half ago, for the details of a very interesting contribution to science, irrespective of

theory. In domestication, this intercrossing may be prevented; and in this prevention lies the art

of producing varieties. But "the art itself is Nature," since the whole art consists in allowing the

most universal of all natural tendencies in organic things (inheritance) to operate uncontrolled

by other and obviously incidental tendencies. No new power, no artificial force, is brought into

play either by separating the stock of a desirable variety so as to prevent mixture, or by

selecting for breeders those individuals which most largely partake of the peculiarities for which

the breed is valued. {I-9]

We see everywhere around us the remarkable results which Nature may be said to have

brought about under artificial selection and separation. Could she accomplish similar results

when left to herself? Variations might begin, we know they do begin, in a wild state. But would

any of them be preserved and carried to an equal degree of deviation? Is there anything in

Nature which in the long-run may answer to artificial selection? Mr. Darwin thinks that there is;

and Natural Selection is the key-note of his discourse,

As a preliminary, he has a short chapter to show that there is variation in Nature, and therefore

something for natural selection to act upon. He readily shows that such mere variations as may

be directly referred to physical conditions (like the depauperation of plants in a sterile soil, or

their dwarfing as they approach an Alpine summit, the thicker fur of an animal from far

northward, etc.), and also those individual differences which we everywhere recognize but do

not pretend to account for, are not separable by any assignable line from more strongly-marked

varieties; likewise that there is no clear demarkation between the latter and sub-species, or

varieties of the highest grade (distinguished from species not by any known inconstancy, but by

the supposed lower importance of their characteristics); nor between these and recognized

species. "These differences blend into each other in an insensible series, and the series

impresses the mind with an idea of an actual passage."

This gradation from species downward is well made out. To carry it one step farther upward,

our author presents in a strong light the differences which prevail among naturalists as to what

forms should be admitted to the rank of species. Some genera (and these in some countries)

give rise to far more discrepancy than others; and it is concluded that the large or dominant

genera are usually the most variable. In a flora so small as the British, 182 plants, generally

reckoned as varieties, have been ranked by some botanists as species. Selecting the British

genera which include the most polymorphous forms, it appears that Babington's Flora gives

them 251 species, Bentham's only 112, a difference of 139 doubtful forms. These are nearly

the extreme views, but they are the views of two most capable and most experienced judges, in

respect to one of the best-known floras of the world. The fact is suggestive, that the best-known

countries furnish the greatest number of such doubtful cases. Illustrations of this kind may be

multiplied to a great extent. They make it plain that, whether species in Nature are aboriginal

and definite or not, our practical conclusions about them, as embodied in systematic works, are

not facts but judgments, and largely fallible judgments-

How much of the actual coincidence of authorities is owing to imperfect or restricted

observation, and to one naturalist's adopting the conclusions of another without independent

observation, this is not the place to consider. It is our impression that species of animals are

more definitely marked than those of plants; this may arise from our somewhat extended

acquaintance with the latter, and our ignorance of the former. But we are constrained by our

experience to admit the strong likelihood, in botany, that varieties on the one hand, and what

are called closely-related species on the other, do not differ except in degree. Whenever this

wider difference separating the latter can be spanned by intermediate forms, as it sometimes is,

no botanist long resists the inevitable conclusion. Whenever, therefore, this wider difference

can be shown to be compatible with community of origin, and explained through natural

selection or in any other way, we are ready to adopt the probable conclusion; and we see

beforehand how strikingly the actual geographical association of related species favors the

broader view. Whether we should continue to regard the forms in question as distinct species,

depends upon what meaning we shall finally attach to that term; and that depends upon how far

the doctrine of derivation can be carried back and how well it can be supported.

In applying his principle of natural selection to the work in hand, Mr. Darwin assumes, as we

have seen: i. Some variability of animals and plants in nature; 2. The absence of any definite

distinction between slight variations, and varieties of the highest grade; 3. The fact that

naturalists do not practically agree, and do not increasingly tend to agree, as to what forms are

species and what are strong varieties, thus rendering it probable that there may be no essential

and original difference, or no possibility of ascertaining it, at least in many cases; also, 4. That

the most flourishing and dominant species of the larger genera on an average vary most (a

proposition which can be substantiated only by extensive comparisons, the details of which are

not given); and, 5. That in large genera the species are apt to be closely but unequally allied

together, forming little clusters round certain species -- just such clusters as would be formed if

we suppose their members once to have been satellites or varieties of a central or parent

species, but to have attained at length a wider divergence and a specific character. The fact of

such association is undeniable; and the use which Mr. Darwin makes of it seems fair and

natural.

The gist of Mr. Darwin's work is to show that such varieties are gradually diverged into species

and genera through natural selection; that natural selection is the inevitable result of the

struggle for existence which all living things are engaged in; and that this struggle is an

unavoidable consequence of several natural causes, but mainly of the high rate at which all

organic beings tend to increase.

Curiously enough, Mr. Darwin's theory is grounded upon the doctrine of Malthus and the

doctrine of Hobbes. The elder DeCandolle had conceived the idea of the struggle for existence,

and, in a passage which would have delighted the cynical philosopher of Malmesbury, had

declared that all Nature is at war, one organism with another or with external Nature; and Lyell

and Herbert had made considerable use of it. But Hobbes in his theory of society, and Darwin

in his theory of natural history, alone have built their systems upon it. However moralists and

political economists may regard these doctrines in their original application to human society

and the relation of population to subsistence, their thorough applicability to the great society of

the organic world in general is now undeniable. And to Mr. Darwin belongs the credit of making

this extended application, and of working out the immensely diversified results with rare

sagacity and untiring patience. He has brought to view real causes which have been largely

operative in the establishment of the actual association and geographical distribution of plants

and animals. In this he must be allowed to have made a very important contribution to an

interesting department of science, even if his theory fails in the endeavor to explain the origin or

diversity of species. "Nothing is easier," says our author, "than to admit in words the truth of

the universal struggle for life, or more difficult -- at least I have found it so -- than constantly to

bear this conclusion in mind. Yet, unless it be thoroughly ingrained in the mind, I am convinced

that the whole economy of Nature, with every fact on distribution, rarity, abundance, extinction,

and variation, will be dimly seen or quite misunderstood. We behold the face of Nature bright

with gladness, we often see superabundance of food; we do not see, or we forget, that the

birds which are idly singing round us mostly live on insects or seeds, and are thus constantly

destroying life; or we forget how largely these songsters, or their eggs, or their nestlings, are

destroyed by birds and beasts of prey; we do not always bear in mind that, though food may be

now superabundant, it is not so at all seasons of each recurring year." -- (p. 62.)

"There is no exception to the rule that every organic being naturally increases at so high a rate

that, if not destroyed, the earth would soon be covered by the progeny of a single pair. Even

slow-breeding man has doubled in twenty-five years, and at this rate, in a few thousand years,

there would literally not be standing-room for his progeny. Linnaeus has calculated that if an

annual plant produced only two seeds -- and there is no plant so unproductive as this -- and

their seedlings next year produced two, and so on, then in twenty years there would be a

million plants. The elephant is reckoned to be the slowest breeder of all known animals, and I

have taken some pains to estimate its pro!)able minimum rate of natural increase; it will be

under the mark to assume that it breeds when thirty years old, and goes on breeding till ninety

years old, bringing forth three pairs of young in this interval; if this be so, at the end of the fifth

century there would be alive fifteen million elephants, descended from the first pair.

"But we have better evidence on this subject than mere theoretical calculations, namely, the

numerous recorded cases of the astonishingly rapid increase of various animals in a state of

nature, when circumstances have been favorable to them during two or three following

seasons. Still more striking is the evidence from our domestic animals of many kinds which

have run wild in several parts of the world; if the statements of the rate of increase of slow-

breeding cattle and horses in , and latterly in , had not been well authenticated, they would

have been quite incredible. So it is with plants: cases could be given of introduced plants which

have become common throughout whole islands in a period of less than ten years. Several of

the plants now most numerous over the wide plains of La Plata, clothing square leagues of

surface almost to the exclusion of all other plants, have been introduced from Europe; and

there are plants which now range in India, as I hear from Dr. Falconer, from Cape Comorin to

the Himalaya, which have been imported from America since its discovery. In such cases, and

endless instances could be given, no one supposes that the fertility of these animals or plants

has been suddenly and temporarily increased in any sensible degree. The obvious explanation

is, that the conditions of life have been very favorable, and that there has consequently been

less destruction of the old and young, and that nearly all the young have been enabled to

breed. In such cases the geometrical ratio of increase, the result of which never fails to be

surprising, simply explains the extraordinarily rapid increase and wide diffusion of naturalized

productions in their new homes." -- (pp. 64, 65.)

"All plants and animals are tending to increase at a geometrical ratio; all would most rapidly

stock any station in which they could anyhow exist; the increase must be checked by

destruction at some period of life." -- (p. 65.)

The difference between the most and the least prolific species is of no account:

"The condor lays a couple of eggs, and the ostrich a score; and yet in the same country the

condor may be the more numerous of the two. The Fulmar petrel lays but one egg, yet it is

believed to be the most numerous bird in the world." -- (p. 68.)

"The amount of food gives the extreme limit to which each species can increase; but very

frequently it is not the obtaining of food, but the serving as prey to other animals, which

determines the average numbers of species." -- (p. 68.)

"Climate plays an important part in determining the average numbers of a species, and

periodical seasons of extreme cold or drought I believe to be the most effective of all checks. I

estimated that the winter of 1854 -- '55 destroyed four-fifths of the birds in my own grounds;

and this is a tremendous destruction, when we remember that ten per cent, is an extraordinarily

severe mortality from epidemics with man. The action of climate seems at first sight to be quite

independent of the struggle for existence; but, in so far as climate chiefly acts in reducing food,

it brings on the most severe struggle between the individuals, whether of the same or of distinct

species, which subsist on the same kind of food, Even when climate, for instance extreme cold,

acts directly, it will be the least vigorous, or those which have got least food through the

advancing winter, which will suffer most. When we travel from south to north, or from a damp

region to a dry, we invariably see some species gradually getting rarer and rarer, and finally

disappearing; and, the change of climate being conspicuous, we are tempted to attribute the

whole effect to its direct action. But this is a very false view; we forget that each species, even

where it most abounds, is constantly suffering enormous destruction at some period of its life,

from enemies or from competitors for the same place and food; and if these enemies or

competitors be in the least degree favored by any slight change of climate, they will increase in

numbers, and, as each area is already stocked with inhabitants, the other species will

decrease. When we travel southward and see a species decreasing in numbers, we may feel

sure that the cause lies quite as much in other species being favored as in this one being hurt.

So it is when we travel northward, but in a somewhat lesser degree, for the number of species

of all kinds, and therefore of competitors, decreases northward; hence, in going northward, or in

ascending a mountain, we far oftener meet with stunted forms, due to the directly injurious

action of climate, than we do in proceeding southward or in descending a mountain. When we

reach the arctic regions, or snow-capped summits, or absolute deserts, the struggle for life is

almost exclusively with the elements.

"That climate acts in main part indirectly by favoring other species, we may clearly see in the

prodigious number of plants in our gardens which can perfectly well endure our climate, but

which never become naturalized, for they cannot compete with our native plants, nor resist

destruction by our native animals." -- (pp. 68, 69.)

After an instructive instance in which "cattle absolutely determine the existence of the Scotch

fir," we are referred to cases in which insects determine the existence of cattle:

"Perhaps Paraguay offers the most curious instance of this; for here neither cattle, nor horses,

nor dogs, have ever run wild, though they swarm southward and northward in a feral state; and

Azara and Rengger have shown that this is caused by the greater number in Paraguay of a

certain fly, which lays its eggs in the navels of these animals when first born. The increase of

these flies, numerous as they are, must be habitually checked by some means, probably by

birds. Hence, if certain insectivorous birds (whose numbers are probably regulated by hawks or

beasts of prey) were to increase in Paraguay, the flies would decrease -- then cattle and horses

would become feral, and this would certainly greatly alter (as indeed I have observed in parts of

South America) the vegetation; this, again, would largely affect the insects; and this, as we

have just seen in Staffordshire, the insectivorous birds, and so onward in ever-increasing

circles of complexity. We began this series by insectivorous birds, and we had ended with

them. Not that in Nature the relations can ever be as simple as this. Battle within battle must

ever be recurring with varying success; and yet in the long-run the forces are so nicely

balanced that the face of Nature remains uniform for long periods of time, though assuredly the

merest trifle would often give the victory to one organic being over another. Nevertheless, so

profound is our ignorance, and so high our presumption, that we marvel when we hear of the

extinction of an organic being; and as we do not see the cause, we invoke cataclysms to

desolate the world, or invent laws on the duration of the forms of life!" -- (pp. 72, 73.)

"When we look at the plants and bushes clothing an entangled bank, we arc tempted to

attribute their proportional numbers and kinds to what we call chance. But how false a view is

this! Every one has heard that when an American forest is cut down, a very different vegetation

springs up; but it has been observed that the trees now growing on the ancient Indian mounds,

in the , display the same beautiful diversity and proportion of kinds as in the surrounding virgin

forests. What a struggle between the several kinds of trees must here have gone on during

long centuries, each annually scattering its seeds by the thousand; what war between insect

and insect -- between insects, snails, and other animals, with birds and beasts of prey -- all

striving to increase, and all feeding on each other or on the trees, or their seeds and seedlings,

or on the other plants which first clothed the ground and thus checked the growth of the trees!

Throw up a handful of feathers, and all must fall to the ground according to definite laws; but

how simple is this problem compared to the action and reaction of the innumerable plants and

animals which have determined, in the course of centuries, the proportional numbers and kinds

of trees now growing on the old Indian ruins!" -- (pp. 74, 75.)

For reasons obvious upon reflection, the competition is often, if not generally, most severe

between nearly related species when they are in contact, so that one drives the other before it,

as the Hanoverian the old English rat, the small Asiatic cockroach in Russia, its greater

congener, etc. And this, when duly considered, explains many curious results; such, for

instance, as the considerable number of different genera of plants and animals which are

generally found to inhabit any limited area.

"The truth of the principle that the greatest amount of life can be supported by great

diversification of structure is seen under many natural circumstances. In an extremely small

area, especially if freely open to immigration, and where the contest between individual and

individual must be severe, we always find great diversity in its inhabitants. For instance, I found

that a piece of turf, three feet by four in size, which had been exposed for many years to exactly

the same conditions, supported twenty species of plants, and these belonged to eighteen

genera, and to eight orders, which showed how much these plants differed from each other. So

it is with the plants and insects on small and uniform islets; and so in small ponds of fresh

water. Farmers find that they can raise most food by a rotation of plants belonging to the most

different orders; Nature follows what may be called a simultaneous rotation. Most of the

animals and plants which live close round any small piece of ground could live on it (supposing

it not to be in any way peculiar in its nature), and may be said to be striving to the utmost to live

there; but it is seen that, where they come into the closest competition with each other, the

advantages of diversification of structure, with the accompanying differences of habit and

constitution, determine that the inhabitants, which thus jostle each other most closely, shall, as

a general rule, belong to what we call different genera and orders." -- (p. 114.)

The abundance of some forms, the rarity and final extinction of many others, and the

consequent divergence of character or increase of difference among the surviving

representatives, are other consequences. As favored forms increase, the less favored must

diminish in number, for there is not room for all; and the slightest advantage, at first probably

inappreciable to human observation, must decide which shall prevail and which must perish, or

be driven to another and for it more favorable locality.

We cannot do justice to the interesting chapter upon natural selection by separated extracts.

The following must serve to show how the principle is supposed to work:

"If during the long course of ages, and under varying conditions of life, organic beings vary at

all in the several parts of their organization, and I think this cannot be disputed; if there be,

owing to the high geometrical powers of increase of each species, at some age, season, or

year, a severe struggle for life, and this certainly cannot be disputed: then, considering the

infinite complexity of the relations of all organic beings to each other and to their conditions of

existence, causing an infinite diversity in structure, constitution, and habits, to be advantageous

to them, I think it would be a most extraordinary fact if no variation ever had occurred useful to

each being's own welfare, in the same way as so many variations have occurred useful to man.

But if variations useful to any organic being do occur, assuredly individuals thus characterized

will have the best chance of being preserved in the struggle for life; and from the strong

principle of inheritance they will tend to produce offspring similarly characterized. This principle

of preservation I have called, for the sake of brevity, Natural Selection." -- (pp. 126, 127.)

"In order to make it clear how, as I believe, natural selection acts, I must beg permission to

give one or two imaginary illustrations. Let us take the case of a wolf, which preys on various

animals, securing some by craft, some by strength, and some by fleetness; and let us suppose

that the fleetest prey, a deer for instance, had from any change in the country increased in

numbers, or that other prey had decreased in numbers, during that season of the year when

the wolf is hardest pressed for food. I can under such circumstances see no reason to doubt

that the swiftest and slimmest wolves would have the best chance of surviving, and so be

preserved or selected -- provided always that they retained strength to master their prey at this

or at some other period of the year, when they might be compelled to prey on other animals. I

can see no more reason to doubt this than that man can improve the fleetness of his

greyhounds by careful and methodical selection, or by that unconscious selection which results

from each man trying to keep the best dogs without any thought of modifying the breed.

"Even without any change in the proportional numbers of the animals on which our wolf preyed,

a cub might be born with an innate tendency to pursue certain kinds of prey. Nor can this be

thought very improbable; for we often observe great differences in the natural tendencies of our

domestic animals: one cat, for instance, taking to catching rats, another mice; one cat,

according to Mr. St. John, bringing home winged game, another hares or rabbits, and another

hunting on marshy ground!, and almost nightly catching woodcocks or snipes. The tendency to

catch rats rather than mice is known to be inherited. Now, if any slight innate change of habit or

of structure benefited an individual wolf, it would have the best chance of surviving and of

leaving offspring. Some of its young would probably inherit the same habits or structure, and by

the repetition of this process a new variety might be formed which would either supplant or

coexist with the parent-form of wolf. Or, again, the wolves inhabiting a mountainous district, and

those frequenting the lowlands, would naturally be forced to hunt different prey; and from a

continued preservation of the individuals best fitted for the two sites, two varieties might slowly

be formed. These varieties would cross and blend where they met; but to this subject of

intercrossing we shall soon have to return. I may add that, according to Mr. Pierce, there are

two varieties of the wolf inhabiting the Catskill Mountains in the United States, one with a light

greyhound-like form, which pursues deer, and the other more bulky, with shorter legs, which

more frequently attacks the shepherd's flock." -- (pp. 90, 91.)

We eke out the illustration here with a counterpart instance, viz., the remark of Dr. Bachman

that "the deer that reside permanently in the swamps of Carolina are taller and longer-legged

than those in the higher grounds." [I-10]

The limits allotted to this article are nearly reached, yet only four of the fourteen chapters of the

volume have been touched. These, however, contain the fundamental principles of the theory,

and most of those applications of it which are capable of something like verification, relating as

they do to the phenomena now occurring. Some of our extracts also show how these principles

are thought to have operated through the long lapse of the ages. The chapters from the sixth to

the ninth inclusive are designed to obviate difficulties and objections, "some of them so grave

that to this day," the author frankly says, he "can never reflect on them without being

staggered." We do not wonder at it. After drawing what comfort he can from "the imperfection of

the geological record" (Chapter IX), which we suspect is scarcely exaggerated, the author

considers the geological succession of organic beings (Chapter X), to see whether they better

accord with the common view of the immutability of species, or with that of their slow and

gradual modification. Geologists must settle that question. Then follow two most interesting and

able chapters on the geographical distribution of plants and animals, the summary of which we

should be glad to cite; then a fitting chapter upon classification, morphology, embryology, etc.,

as viewed in the light of this theory, closes the argument; the fourteenth chapter being a

recapitulation.

The interest for the general reader heightens as the author advances on his perilous way and

grapples manfully with the most formidable difficulties.

To account, upon these principles, for the gradual elimination and segregation of nearly allied

forms -- such as varieties, sub-species, and closely-related or representative species -- also in

a general way for their geographical association and present range, is comparatively easy, is

apparently within the bounds of possibility. Could we stop here we should be fairly contented.

But, to complete the system, to carry out the principles to their ultimate conclusion, and to

explain by them many facts in geographical distribution which would still remain anomalous, Mr.

Darwin is equally bound to account for the formation of genera, families, orders, and even

classes, by natural selection. He does "not doubt that the theory of descent with modification

embraces all the members of the same class," and he concedes that analogy would press the

conclusion still further; while he admits that "the more distinct the forms are, the more the

arguments fall away in force." To command assent we naturally require decreasing probability

to be overbalanced by an increased weight of evidence. An opponent might plausibly, and

perhaps quite fairly, urge that the links in the chain of argument are weakest just where the

greatest stress falls upon them.

To which Mr. Darwin's answer is, that the best parts of the testimony have been lost. He is

confident that intermediate forms must have existed; that in the olden times when the genera,

the families, and the orders, diverged from their parent stocks, gradations existed as fine as

those which now connect closely related species with varieties. But they have passed and left

no sign. The geological record, even if all displayed to view, is a book from which not only many

pages, but even whole alternate chapters, have been lost out, or rather which were never

printed from the autographs of Nature. The record was actually made in fossil lithography only

at certain times and under certain conditions (i.e., at periods of slow subsidence and places of

abundant sediment); and of these records all but the last volume is out of print; and of its pages

only local glimpses have been obtained. Geologists, except Lyell, will object to this -- some of

them moderately, others with vehemence. Mr. Darwin himself admits, with a candor rarely

displayed on such occasions, that he should have expected more geological evidence of

transition than he finds, and that all the most eminent paleontologists maintain the immutability

of species.

The general fact, however, that the fossil fauna of each period as a whole is nearly intermediate

in character between the preceding and the succeeding faunas, is much relied on. We are

brought one step nearer to the desired inference by the similar "fact, insisted on by all

paleontologists, that fossils from two consecutive formations are far more closely related to

each other than are the fossils of two remote formations. Pictet gives a well-known instance --

the general resemblance of the organic remains from the several stages of the chalk formation,

though the species are distinct at each stage. This fact alone, from its generality, seems to

have shaken Prof. Pictet in his firm belief in the immutability of species" (p. 335). What Mr.

Darwin now particularly wants to complete his inferential evidence is a proof that the same

gradation may be traced in later periods, say in the Tertiary, and between that period and the

present; also that the later gradations are finer, so as to leave it doubtful whether the

succession is one of species -- believed on the one theory to be independent, on the other,

derivative -- or of varieties, which are confessedly derivative. The proof of the finer gradation

appears to be forthcoming. Des Hayes and Lyell have concluded that many of the middle

Tertiary and a large proportion of the later Tertiary mollusca are specifically identical with living

species; and this is still the almost universally prevalent view. But Mr. Agassiz states that, "in

every instance where he had sufficient materials, he had found that the species of the two

epochs supposed to be identical by Des Hayes and Lyell were in reality distinct, although

closely allied species."[I-11] Moreover, he is now satisfied, as we understand, that the same

gradation is traceable not merely in each great division of the Tertiary, but in particular deposits

or successive beds, each answering to a great number of years; where what have passed

unquestioned as members of one species, upon closer examination of numerous specimens

exhibit differences which in his opinion entitle them to be distinguished into two, three, or more

species. It is plain, therefore, that whatever conclusions can be fairly drawn from the present

animal and vegetable kingdoms in favor of a gradation of varieties into species, or into what

may be regarded as such, the same may be extended to the Tertiary period. In both cases,

what some call species others call varieties; and in the later Tertiary shells this difference in

judgment affects almost half of the species!

We pass to a second difficulty in the way of Mr. Darwin's theory; to a case where we are

perhaps entitled to demand of him evidence of gradation like that which connects the present

with the Tertiary mollusca. Wide, very wide is the gap, anatomically and physiologically (we do

not speak of the intellectual) between the highest quadrumana and man; and comparatively

recent, if ever, must the line have bifurcated. But where is there the slightest evidence of a

common progenitor? Perhaps Mr. Darwin would reply by another question: where are the fossil

remains of the men who made the flint knives and arrowheads of the Somme Valley?

We have a third objection, one, fortunately, which has nothing to do with geology. We can only

state it here in brief terms. The chapter on hybridism is most ingenious, able, and instructive. If

sterility of crosses is a special original arrangement to prevent the confusion of species by

mingling, as is generally assumed, then, since varieties cross readily and their offspring is

fertile inter se, there is a fundamental distinction between varieties and species. Mr. Darwin

therefore labors to show that it is not a special endowment, but an incidental acquirement. He

does show that the sterility of crosses is of all degrees; upon which we have only to say, Natura

non facit saltum, here any more than elsewhere. But, upon his theory he is bound to show how

sterility might be acquired, through natural selection or through something else. And the

difficulty is, that, whereas individuals of the very same blood tend to be sterile, and somewhat

remoter unions diminish this tendency, and when they have diverged into two varieties the

cross-breeds between the two are more fertile than either pure stock -- yet when they have

diverged only one degree more the whole tendency is reversed, and the mongrel is sterile,

either absolutely or relatively. He who explains the genesis of species through purely natural

agencies should assign a natural cause for this remarkable result; and this Mr. Darwin has not

done. Whether original or derived, however, this arrangement to keep apart those forms which

have, or have acquired (as the case may be), a certain moderate amount of difference, looks to

us as much designed for the purpose, as does a rachet to prevent reverse motion in a wheel. If

species have originated by divergence, this keeps them apart.

Here let us suggest a possibly attainable test of the theory of derivation, a kind of instance

which Mr. Darwin may be fairly asked to produce -- viz., an instance of two varieties, or what

may be assumed as such, which have diverged enough to reverse the movement, to bring out

some sterility in the crosses. The best marked human races might offer the most likely case. If

mulattoes are sterile or tend to sterility, as some naturalists confidently assert, they afford Mr.

Darwin a case in point. If, as others think, no such tendency is made out, the required evidence

is wanting.

A fourth and the most formidable difficulty is that of the production and specialization of organs.

It is well said that all organic beings have been formed on two great laws: unity of type, and

adaptation to the conditions of existence.[I-12] The special teleologists, such as Paley, occupy

themselves with the latter only; they refer particular facts to special design, but leave an

overwhelming array of the widest facts inexplicable. The morphologists build on unity of type, or

that fundamental agreement in the structure of each great class of beings which is quite

independent of their habits or conditions of life; which requires each individual "to go through a

certain formality," and to accept, at least for a time, certain organs, whether they are of any use

to him or not. Philosophical minds form various conceptions for harmonizing the two views

theoretically. Mr. Darwin harmonizes and explains them naturally. Adaptation to the conditions

of existence is the result of natural selection; unity of type, of unity of descent. Accordingly, as

he puts his theory, he is bound to account for the origination of new organs, and for their

diversity in each great type, for their specialization, and every adaptation of organ to function

and of structure to condition, through natural agencies. Whenever he attempts this he reminds

us of Lamarck, and shows us how little light the science of a century devoted to structural

investigation has thrown upon the mystery of organization. Here purely natural explanations fail.

The organs being given, natural selection may account for some improvement; if given of a

variety of sorts or grades, natural selection might determine which should survive and where it

should prevail.

On all this ground the only line for the theory to take is to make the most of gradation and

adherence to type as suggestive of derivation, and unaccountable upon any other scientific

view -- deferring all attempts to explain how such a metamorphosis was effected, until

naturalists have explained how the tadpole is metamorphosed into a frog, or one sort of polyp

into another. As to why it is so, the philosophy of efficient cause, and even the whole argument

from design, would stand, upon the admission of such a theory of derivation, precisely where

they stand without it. At least there is, or need be, no ground of difference here between Darwin

and Agassiz. The latter will admit, with Owen and every morphologist, that hopeless is the

attempt to explain the similarity of pattern in members of the same class by utility or the

doctrine of final causes. "On the ordinary view of the independent creation of each being, we

can only say that so it is, that it has so pleased the Creator to construct each animal and plant."

Mr. Darwin, in proposing a theory which suggests a how that harmonizes these facts into a

system, we trust implies that all was done wisely, in the largest sense designedly, and by an

intelligent first cause. The contemplation of the subject on the intellectual side, the amplest

exposition of the unity of plan in creation, considered irrespective of natural agencies, leads to

no other conclusion.

We are thus, at last, brought to the question, What would happen if the derivation of species

were to be substantiated, either as a true physical theory, or as a sufficient hypothesis? What

would come of it? The inquiry is a pertinent one, just now. For, of those who agree with us in

thinking that Darwin has not established his theory of derivation many will admit with us that he

has rendered a theory of derivation much less improbable than before; that such a theory

chimes in with the established doctrines of physical science, and is not unlikely to be largely

accepted long before it can be proved. Moreover, the various notions that prevail -- equally

among the most and the least religious -- as to the relations between natural agencies or

phenomena and efficient cause, are seemingly more crude, obscure, and discordant, than they

need be.

It is not surprising that the doctrine of the book should be denounced as atheistical. What does

surprise and concern us is, that it should be so denounced by a scientific man, on the broad

assumption that a material connection between the members of a series of organized beings is

inconsistent with the idea of their being intellectually connected with one another through the

Deity, i.e., as products of one mind, as indicating and realizing a preconceived plan. An

assumption the rebound of which is somewhat fearful to contemplate, but fortunately one which

every natural birth protests against.

It would be more correct to say that the theory in itself is perfectly compatible with an atheistic

view of the universe. That is true; but it is equally true of physical theories generally. Indeed, it

is more true of the theory of gravitation, and of the nebular hypothesis, than of the hypothesis in

question. The latter merely takes up a particular, proximate cause, or set of such causes, from

which, it is argued, the present diversity of species has or may have contingently resulted. The

author does not say necessarily resulted; that the actual results in mode and measure, and

none other, must have taken place. On the other hand, the theory of gravitation and its

extension in the nebular hypothesis assume a universal and ultimate physical cause, from

which the effects in Nature must necessarily have resulted. Now, it is not thought, at least at

the present day, that the establishment of the Newtonian theory was a step toward atheism or

pantheism. Yet the great achievement of Newton consisted in proving that certain forces (blind

forces, so far as the theory is concerned), acting upon matter in certain directions, must

necessarily produce planetary orbits of the exact measure and form in which observation shows

them to exist -- a view which is just as consistent with eternal necessity, either in the atheistic or

the pantheistic form, as it is with theism.

Nor is the theory of derivation particularly exposed to the charge of the atheism of fortuity; since

it undertakes to assign real causes for harmonious and systematic results. But, of this, a word

at the close.

The value of such objections to the theory of derivation may be tested by one or two analogous

cases. The common scientific as well as popular belief is that of the original, independent

creation of oxygen and hydrogen, iron, gold, and the like. Is the speculative opinion now

increasingly held, that some or all of the supposed elementary bodies are derivative or

compound, developed from some preceding forms of matter, irreligious? Were the old

alchemists atheists as well as dreamers in their attempts to transmute earth into gold? Or, to

take an instance from force (power) -- which stands one step nearer to efficient cause than

form -- was the attempt to prove that heat, light, electricity, magnetism, and even mechanical

power, are variations or transmutations of one force, atheistical in its tendency? The supposed

establishment of this view is reckoned as one of the greatest scientific triumphs of this century.

Perhaps, however, the objection is brought, not so much against the speculation itself, as

against the attempt to show how derivation might have been brought about. Then the same

objection applies to a recent ingenious hypothesis made to account for the genesis of the

chemical elements out of the ethereal medium, and to explain their several atomic weights and

some other characteristics by their successive complexity -- hydrogen consisting of so many

atoms of ethereal substance united in a particular order, and so on. The speculation interested

the philosophers of the British Association, and was thought innocent, but unsupported by

facts. Surely Mr. Darwin's theory is none the worse, morally, for having some foundation in fact.

In our opinion, then, it is far easier to vindicate a theistic character for the derivative theory,

than to establish the theory itself upon adequate scientific evidence. Perhaps scarcely any

philosophical objection can be urged against the former to which the nebular hypothesis is not

equally exposed. Yet the nebular hypothesis finds general scientific acceptance, and is adopted

as the basis of an extended and recondite illustration in Mr. Agassiz's great work.[I-13]

How the author of this book harmonizes his scientific theory with his philosophy and theology,

he has not informed us. Paley in his celebrated analogy with the watch, insists that if the

timepiece were so constructed as to produce other similar watches, after a manner of

generation in animals, the argument from design would be all the stronger. What is to hinder

Mr. Darwin from giving Paley's argument a further a-fortiori extension to the supposed case of a

watch which sometimes produces better watches, and contrivances adapted to successive

conditions, and so at length turns out a chronometer, a town clock, or a series of organisms of

the same type? From certain incidental expressions at the close of the volume, taken in

connection with the motto adopted from Whewell, we judge it probable that our author regards

the whole system of Nature as one which had received at its first formation the impress of the

will of its Author, foreseeing the varied yet necessary laws of its action throughout the whole of

its existence, ordaining when and bow each particular of the stupendous plan should be

realized in effect, and -- with Him to whom to will is to do -- in ordaining doing it, Whether

profoundly philosophical or not, a view maintained by eminent philosophical physicists and

theologians, such as Babbage on the one hand and Jowett on the other, will hardly be

denounced as atheism. Perhaps Mr. Darwin would prefer to express his idea in a more general

way, by adopting the thoughtful words of one of the most eminent naturalists of this or any age,

substituting the word action for "thought," since it is the former (from which alone the latter can

be inferred) that he has been considering. "Taking Nature as exhibiting thought for my guide, it

appears to me that while human thought is consecutive, Divine thought is simultaneous,

embracing at the same time and forever, in the past, the present and the future, the most

diversified relations among hundreds of thousands of organized beings, each of which may

present complications again, which to study and understand even imperfectly -- as for instance

man himself -- mankind has already spent thousands of years."[I-14] In thus conceiving of the

Divine Power in act as coetaneous with Divine Thought, and of both as far as may be apart

from the human element of time, our author may regard the intervention of the Creator either

as, humanly speaking, done from all time, or else as doing through all time. In the ultimate

analysis we suppose that every philosophical theist must adopt one or the other conception.

A perversion of the first view leads toward atheism, the notion of an eternal sequence of cause

and effect, for which there is no first cause -- a view which few sane persons can long rest in.

The danger which may threaten the second view is pantheism. We feel safe from either error, in

our profound conviction that there is order in the universe; that order presupposes mind;

design, will; and mind or will, personality. Thus guarded, we much prefer the second of the two

conceptions of causation, as the more philosophical as well as Christian view -- a view which

leaves us with the same difficulties and the same mysteries in Nature as in , and no other.

Natural law, upon this view, is the human conception of continued and orderly Divine action.

We do not suppose that less power, or other power, is required to sustain the universe and

carry on its operations, than to bring it into being. So, while conceiving no improbability of

"interventions of Creative mind in Nature," if by such is meant the bringing to pass of new and

fitting events at fitting times, we leave it for profounder minds to establish, if they can, a rational

distinction in kind between his working in Nature carrying on operations, and in initiating those

operations.

We wished, under the light of such views, to examine more critically the doctrine of this book,

especially of some questionable parts; for instance, its explanation of the natural development

of organs, and its implication of a "necessary acquirement of mental power" in the ascending

scale of gradation. But there is room only for the general declaration that we cannot think the

Cosmos a series which began with chaos and ends with mind, or of which mind is a result: that,

if, by the successive origination of species and organs through natural agencies, the author

means a series of events which succeed each other irrespective of a continued directing

intelligence -- events which mind does not order and shape to destined ends -- then he has not

established that doctrine, nor advanced toward its establishment, but has accumulated

improbabilities beyond all belief. Take the formation and the origination of the successive

degrees of complexity of eyes as a specimen. The treatment of this subject (pp. i88, 189), upon

one interpretation, is open to all the objections referred to; but, if, on the other hand, we may

rightly compare the eye "to a telescope, perfected by the long-continued efforts of the highest

human intellects," we could carry out the analogy, and draw satisfactory illustrations and

inferences from it. The essential, the directly intellectual thing is the making of the

improvements in the telescope or the steam-engine. Whether the successive improvements,

being small at each step, and consistent with the general type of the instrument, are applied to

some of the individual machines, or entire new machines are constructed for each, is a minor

matter. Though, if machines could engender, the adaptive method would be most economical;

and economy is said to be a paramount law in Nature. The origination of the improvements,

and the successive adaptations to meet new conditions or subserve other ends, are what

answer to the supernatural, and therefore remain inexplicable. As to bringing them into use,

though wisdom foresees the result, the circumstances and the natural competition will take care

of that, in the long-run. The old ones will go out of use fast enough, except where an old and

simple machine remains still best adapted to a particular purpose or condition -- as, for

instance, the old Newcomen engine for pumping out coal-pits. If there's a Divinity that shapes

these ends, the whole is intelligible and reasonable; otherwise, not.

We regret that the necessity of discussing philosophical questions has prevented a fuller

examination of the theory itself, and of the interesting scientific points which are brought to bear

in its favor. One of its neatest points, certainly a very strong one for the local origination of

species, and their gradual diffusion under natural agencies, we must reserve for some other

convenient opportunity.

The work is a scientific one, rigidly restricted to its direct object; and by its science it must stand

or fall. Its aim is, probably, not to deny creative intervention in Nature -- for the admission of the

independent origination of certain types does away with all antecedent improbability of as much

intervention as may be required -- but to maintain that Natural Selection, in explaining the facts,

explains also many classes of facts which thousand-fold repeated independent acts of creation

do not explain, but leave more mysterious than ever. How far the author has succeeded, the

scientific world will in due time be able to pronounce.

As these sheets are passing through the press, a copy of the second edition has reached us.

We notice with pleasure the insertion of an additional motto on the reverse of the title page,

directly claiming the theistic view which we have vindicated for the doctrine. Indeed, these

pertinent words of the eminently wise Bishop Butler comprise, in their simplest expression, the

whole substance of our later pages:

"The only distinct meaning of the word 'natural' is stated, fixed, or settled; since what is natural

as much requires and presupposes an intelligent mind to render it so, i.e., to effect it continually

or at stated times, as what is supernatural or miraculous does to effect it for once."

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