which nevertheless we generally admit to have arisen through ordinary generation, we ought not to lay too much stress on our ignorance of the precise cause of the slight analogous differences between species. I might have adduced for this same purpose the differences between the races of man, which are so strongly marked; I may add that some little light can apparently be thrown on the origin of these differences, chiefly through sexual selection of a particular kind, but without here entering on copious details my reasoning would appear frivolous.

Utilitarian Doctrine how far true: Beauty how acquired.

The foregoing remarks lead me to say a few words on the protest lately made by some naturalists, against the utilitarian doctrine that every detail of structure has been produced for the good of its possessor. They believe that very many structures have been created for beauty in the eyes of man, or, as already mentioned and discussed, for the sake of mere variety. Such doctrines, if true, would be absolutely fatal to my theory. Yet I fully admit that many structures are of no direct use to their possessors. Physical conditions probably have had some little direct effect on structure, quite independently of any good thus gained. Correlation of growth no doubt has largely come into action, and a useful modification of one part has often entailed on other parts changes of structure of no direct use. So again characters which formerly were useful, or which formerly had arisen from correlation of growth, or from other unknown causes, may reappear from the law of reversion, though now of no direct use. But by far the most important consideration is that the chief part of the organisation of every being is simply due to inheritance; and consequently, though each being

assuredly is well fitted for its place in nature, many structures now have no direct relation to the habits of life of each species. Thus, we can hardly believe that the webbed feet of the upland goose or of the frigatebird are of special use to these birds; we cannot believe that the similar bones in the arm of the monkey, in the fore-leg of the horse, in the wing of the bat, and in the flipper of the seal, are of special use to these animals. We may safely attribute these structures to inheritance. But to the progenitor of the upland goose and of the frigate-bird, webbed feet no doubt were as useful as they now are to the most aquatic of existing birds. So we may believe that the progenitor of the seal had not a flipper, but a foot with five toes fitted for walking or grasping; and we may further venture to believe that the several bones in the limbs of the monkey, horse, and bat, which have been inherited from a common progenitor, were formerly of more special use to that progenitor, or its progenitors, than they now are to these animals having such widely diversified habits. Therefore we may infer that these several bones might have been acquired through natural selection, subjected formerly, as now, to the several laws of inheritance, reversion, correlation of growth, &c. Hence every detail of structure in every living creature (making some little allowance for the direct action of physical conditions) may be viewed, either as having been of special use to some ancestral form, or as being now of special use to the descendants of this form-either directly, or indirectly through the complex laws of growth.

With respect to the view that organic beings have been created beautiful for the delight of man, a view which it has lately been pronounced may safely be accepted as true, and as subversive of my whole theory, -I may first remark that the idea of the beauty of any

particular object obviously depends on the mind of man, irrespective of any real quality in the admired object; and that the idea is not an innate and unalterable element in the mind. We see this in men of different races admiring an entirely different standard of beauty in their women; neither the Negro nor the Chinese admires the Caucasian beau-ideal. The idea also of beauty in natural scenery has arisen only within modern times. On the view of beautiful objects having been created for man's gratification, it ought to be shown that there was less beauty on the face of the earth before man appeared than since he came on the stage. Were the beautiful volute and cone shells of the Eocene epoch, and the gracefully sculptured ammonites of the Secondary period, created that man might ages afterwards admire them in his cabinet? Few objects are more beautiful than the minute siliceous cases of the diatomacea were these created that they might be examined and admired under the higher powers of the microscope? The beauty in this latter case, and in many others, is apparently wholly due to symmetry of growth. Flowers rank amongst the most beautiful productions of nature; and they have become through natural selection beautiful, or rather conspicuous in contrast with the greenness of the leaves, that they might be easily observed and visited by insects, so that their fertilisation might be favoured. I have come to this conclusion from finding it an invariable rule that when a flower is fertilised by the wind it never has a gaily-coloured corolla. Again, several plants habitually produce two kinds of flowers; one kind open and coloured so as to attract insects; the other closed and not coloured, destitute of nectar, and never visited by insects. We may safely conclude that, if insects had never existed on the face of the earth, the vegetation

eye

would not have been decked with beautiful flowers, but would have produced only such poor flowers as are now borne by our firs, oaks, nut and ash trees, by the grasses, by spinach, docks, and nettles. A similar line of argument holds good with the many kinds of beautiful fruits; that a ripe strawberry or cherry is as pleasing to the as to the palate, that the gaily-coloured fruit of the spindle-wood tree and the scarlet berries of the holly are beautiful objects, will be admitted by every one. But this beauty serves merely as a guide to birds and beasts, that the fruit may be devoured and the seeds thus disseminated: I infer that this is the case from having as yet found in every instance that seeds, which are embedded within a fruit of any kind, that is within a fleshy or pulpy envelope, if it be coloured of any brilliant tint, or merely rendered conspicuous by being coloured white or black, are always disseminated by being first devoured.

On the other hand, I willingly admit that a great number of male animals, as all our most gorgeous birds, certainly some fishes, perhaps some mammals, and a host of magnificently coloured butterflies and some other insects, have been rendered beautiful for beauty's sake; but this has been effected not for the delight of man, but through sexual selection, that is from the more beautiful males having been continually preferred by their less ornamented females. So it is with the music of birds. We may infer from all this that a similar taste for beautiful colours and for musical sounds runs through a large part of the animal kingdom. When the female is as beautifully coloured as the male, which is not rarely the case with birds and butterflies, the cause simply lies in the colours acquired through sexual selection having been inherited by both sexes, instead of by the males alone. We can sometimes plainly see

the proximate cause of the transmission of ornaments to the males alone; for a pea-hen with the long tail of the male bird would be badly fitted to sit on her eggs, and a coal-black female capercailzie would be far more conspicuous on her nest and more exposed to danger than in her present modest attire.

Natural selection cannot possibly produce any modification in any one species exclusively for the good of another species; though throughout nature one species incessantly takes advantage of, and profits by, the structure of another. But natural selection can and does often produce structures for the direct injury of other species, as we see in the fang of the adder, and in the ovipositor of the ichneumon, by which its eggs are deposited in the living bodies of other insects. If it could be proved that any part of the structure of any one species had been formed for the exclusive good of another species, it would annihilate my theory, for such could not have been produced through natural selection. Although many statements may be found in works on natural history to this effect, I cannot find even one which seems to me of any weight. It is admitted that the rattlesnake has a poison-fang for its own defence and for the destruction of its prey; but some authors suppose that at the same time this snake is furnished with a rattle for its own injury, namely, to warn its prey to escape. I would almost as soon believe that the cat curls the end of its tail when preparing to spring, in order to warn the doomed mouse. But I have not space here to enter on this and other such cases.

Natural selection will never produce in a being anything injurious to itself, for natural selection acts solely by and for the good of each. No organ will be formed, as Paley has remarked, for the purpose of causing pain or for doing an injury to its possessor. If a fair balance

M