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feel it right to limit our discussion of it to an examination of the soundness of the main principle on which it is based. nute criticism of details would, as it seems to us, be at present altogether misplaced. Indeed, we almost regret that the author has as yet gone into detail at all, since he has laid himself open to a great deal of objection on the score of minor difficulties, which will tend to prevent his fundamental doctrine from finding candid appreciation. And we cannot help thinking that it might have been better if, in this early stage of the inquiry, Mr. Darwin, like Mr. Wallace, had abstained from that explicit avowal of the ultimate conclusions to which it seems to him to lead, which will be pretty sure at once to frighten away many whom he might have otherwise obtained as adherents. Of course, if his principle be firmly based on truth, every thing that is legitimately deducible from it must also be true. But as it is in the nature of things impossible to obtain any thing like positive evidence on the remoter issues of the inquiry, we shall discard for the present all reference to the question whether (as Mr. Darwin thinks probable) men and tadpoles, birds and fishes, spiders and snails, insects and oysters, encrinites and sponges, had a common origin in the womb of time, and shall address ourselves only to the arguments urged by Mr. Darwin and Mr. Wallace in support of their doctrine of the modification of specific types by natural selection.

To such as look upon this question from the purely scientific point of view, any theological objection, even to Mr. Darwin's rather startling conclusion, much more to his very modest premises, seems simply absurd. We never heard of any body who thought that a religious question was involved in the inquiry whether our breeds of dog are derived from one or from several ancestral stocks; nor should we suppose that the stoutest believers in the Mosaic cosmogony would be much dismayed if it could be shown that the dog is really a derivation from the wolf. Orthodoxy (on this side of the Atlantic at least) is decidedly in favour of the abolition of the two-andtwenty species into which man has been divided by some zoologists, and of the reference of all the strongly-diversified races of man to the Adamic stock. We do not expect to see, even in our "most straitest" sectarian organs, any accusations brought against Mr. Bentham for impiety, because he affirms that three or four hundred of the reputed species of British plants are really descendants of others from which they have gradually diverged; and if he were led by the results of further inquiry to knock off as many more, we believe that he would be left to the criticism of his brother botanists, and that his British Flora would not run any risk of being put into the

Index Expurgatorius, alongside of Lamarck's Philosophie Zoologique and the Vestiges of the Natural History of Creation.

Why, then, should Mr. Darwin be attacked (as he most assuredly will be) for venturing to carry the same method of inquiry a step further; and be accused (in terms which it needs no spirit of prophecy to anticipate) of superseding the functions of the Creator, of blotting out his Attributes from the page of Nature, and of reducing Him to the level of a mere Physical Agency? To our apprehension, the Creator did not finish his labours with the creation of the protoplasts of each species; his work is always in progress; the origin and development of each new being that comes into life, is a new manifestation of his creative power; and the question is simply as to the mode in which it has pleased Him to exercise that power; whether, according to common ideas, He has every now and then swept off a greater or smaller proportion of the inhabitants of the globe, and has replaced them by new forms, brought into existence in some mode altogether unknown to us; or whether, as Mr. Darwin maintains, the apparent introduction of new forms has really been brought about by a gradual and successive modification of the old. For ourselves, we do not hesitate to say that the orderly and continuous working out of any plan which could evolve such harmony and completeness of results as the world of Nature (present and past) spreads out before us, is far more consistent with our idea of that Being who "knows no variableness, neither shadow of turning," than the intermittent action of a power that requires a succession of interferences to carry out its original design in conformity with successive changes in the physical conditions of the globe. And we have no sympathy with those who, to use the admirable language of Professor Powell (whose Essay on the Philosophy of Creation contains a masterly refutation of the current theological arguments bearing on this question), maintain that we "behold the Deity more clearly in the dark than in the light,-in confusion, interruption, and catastrophe, more than in order, continuity, and progress."

Our knowledge as to the Variability of Species in Time is of course mainly derived from observation of the changes induced by the agency of Man, in those species of plants and animals which have been longest subjected to the influence of cultivation and domestication; and although it may be questioned how far the modifications thus induced would tend to perpetuate themselves in a state of nature, yet we cannot shut our eyes to the fact that the capacity for undergoing such modifications under conditions how artificial soever, exhibits an elasticity of constitution which would equally tend to adapt these

animals to varieties of natural conditions, and thus to originate diversified races which would perpetuate themselves without man's interference. It may be well to adduce a few examples, in which peculiarities of organisation or constitution have sprung up and perpetuated themselves under the notice of competent witnesses. Such peculiarities have been ranked in two categories: those, namely, which are obviously "acquired" under the direct influence of external agencies; and those which, not seeming likely to have been thus occasioned, are spoken of as "spontaneous," or "accidental."

Of the acquirement of peculiarities, we have frequent experience in the changes which animals and plants undergo when they are transported to regions differing greatly in climatic conditions from those they previously inhabited. Thus the longest-woolled sheep that can be brought from Leicestershire or Sussex to the West Indies have their thick matted fleeces replaced in a year or two by short crisp hair; and in the lambs bred in their new country this hair is so brown as to render it somewhat difficult to distinguish them from the kids of the goats with which they are often seen associated. Sometimes the acclimatising process does not modify the character of the parent, but takes effect only on the young, born and bred under its influence. Thus, in a well-known case related. by Sir C. Lyell, the English greyhounds that were taken out to hunt the hares which abound on a table-land in Mexico at an elevation of 9000 feet, were distanced in the chase by want of wind; yet the offspring of these same animals are not in the least incommoded by the rarity of the atmosphere in which they have passed their whole lives, but run down the hares with as much ease as the fleetest of their race in this country.

But peculiarities every now and then appear in the offspring at birth, which, not being traceable to any corresponding change of circumstances, are commonly regarded as "freaks of Nature;" such, for example, as the presence of a sixth finger, or of an additional joint in the thumb, on the human hand; or of that peculiar conformation of the limbs that distinguishes the "ancon" breed of sheep in New England; or the so-called "sporting" varieties of plants. No one, however, who believes in the universality of causation, can fail to perceive on reflection, that any such congenital peculiarities, like the differences among individuals of the same parentage, must have had their origin in the condition of the one or both parents at the time of procreation; and this inference is fully borne out by the special tendency of such peculiarities to become hereditary, though they frequently pass over a generation or two, to reappear in a subsequent one. The latency of such influences is often ex

tremely remarkable; but sometimes we seem able to trace out their nature, though we cannot comprehend their mode of operation. Thus there is valid scientific evidence that the colour of the offspring of animals whose hue is disposed to vary, is influenced by strong mental impressions on the parents; and that it is in this way that variety of hue was first engendered in races previously of uniform colour, would seem to be indicated by the fact related by Mr. T. Bell, that a litter of puppies born in the Zoological Gardens from a male and female Australian dingo of pure breed, both of which were of the uniform reddish-brown hue that belongs to the race (the mother never having bred before), were all more or less spotted.

Now the art of the breeder consists first in carefully watching for this spontaneous appearance of any such peculiarities as he may deem it profitable to introduce, which then, by taking advantage of their tendency to become hereditary, especially when they are possessed by both parents, he establishes as the distinctive feature of a new race; and in this race he preserves them in full force by a rigorous weeding out of all the individuals which do not possess them. We cannot have a better example of this process than the recent creation of the Mauchamp breed of sheep, which produces a fine silky wool, distinguished by the strength as well as by the length and fineness of its fibre, and specially valuable for the manufacture of Cashmere shawls. In the year 1828, one of the ewes of the flock of merino sheep belonging to M. Graux, a farmer of Mauchamp, produced a male lamb, which, as it grew up, became remarkable for the silky character of its wool, and for the shortness of its horns; it was of small size, and of inferior general conformation. Desiring, however, to obtain other sheep having the same quality of wool, M. Graux determined to breed from this ram : at first he only obtained it in a single ram and a single ewe; in subsequent years he got it in a larger proportion of each progeny; and as his silky-woolled sheep multiplied, he was able to secure a constant succession by matching them with each other. Amongst the breed thus engendered, some resembled the ancestral ram in its physical defects as well as in its wool; but others, while possessing the same character of wool, reverted to the more symmetrical form of the breed from which this was an offset; and M. Graux, by a judicious system of crossing and intercrossing, at last established a race which not only possesses the silky wool of the first ram without the least deterioration, but is entirely free from its defects of general conformation.

The agency of Man in this procedure is that of accumulative selection. He can do nothing except on the basis of variations which are first given to him in some slight degree by nature

(the origin of such variations, however, being in the modifications induced by external conditions in the procreative action of the parents); these, which would soon disappear if left to themselves, by merging in the general aggregate, he not only perpetuates by selection, but augments by accumulation, adding them up (as Mr. Darwin felicitously phrases it) in certain directions useful to him. Now there are instances in which varieties have been thus engendered, differing so much from their original stock and from each other, that, if they were to be placed before a zoologist ignorant of their genetic relationship, he would unquestionably rank them not only as distinct species, but even as belonging to distinct genera. This is the case, for example, with the various heads of pigeons, which have been closely studied by Mr. Darwin. The English carrier, the short-faced tumbler, the runt, the barb, the pouter, and the fantail, differ from each other not merely in their plumage, but in those points of conformation of beak and skull on which generic distinctions among birds are chiefly founded; and subordinate to each of these breeds are several regularly propagating sub-breeds, which differ as much from each other in characters of minor importance as species do elsewhere. Yet there is no ground for questioning the general belief of scientific ornithologists, that all these breeds have had their origin in the rock pigeon; especially as the comparison of a large number of individuals of these breeds and sub-breeds, including those brought from distant countries, would enable an almost perfect gradational series to be formed between the types that differ most widely in structure.

It is obvious, then, that by such a process what we may designate as Naturalists' species might be artificially created to any extent. The question now arises, whether truly Natural Species can have been engendered in a similar manner; that is to say, whether any thing like accumulative selection has gone on amongst plants and animals in their feral state, by which the vast multitude of diverse forms now existing may have been evolved from a comparatively small number of original types, and that wonderful series of extinct forms may have been produced, which palæontology reveals to us as having peopled and repeopled our globe many times through the immeasurable succession of geological ages.

The answer to this question, according both to Mr. Darwin and Mr. Wallace, is to be found in a careful examination of the facts relating to the Struggle for Existence which all wild animals have to maintain. "The full exertion of all their faculties and all their energies," it is observed by Mr. Wallace, "is required to preserve their own existence, and provide for that of their in