or spectres, to which this insect belongs, is more or less imitative, and a great number of the species are called walking-stick insects,' from their singular resemblance to twigs and branches." Again, Mr. Wallace tells us of as many as four kinds of orioles, which birds mimic, more or less, four species of a genus of honey-suckers, the weak orioles finding their profit in being mistaken by certain birds of prey for the strong, active, and gregarious honey-suckers. Now many other birds would be benefited by similar mimicry, which is none the less confined, in this part of the world, to the oriole genus. It is true that the absence of mimicry in "Malay Archipelago," vol. ii. p. 150; and "Natural Selection," p. 104. THE RED BIRD OF PARADISE. other forms may be explained by their possessing some other (as yet unobserved) means of preservation; but it is nevertheless remarkable, not so much that one species should mimic, as that no less than four should do so in different ways and degrees, all these four belonging to one and the same genus. In other cases, however, there is not even the help of protective action to account for the phenomenon. Thus we have the wonderful birds of Paradise, which agree in developing plumage unequalled in beauty, but a beauty 1 See "Malay Archipelago," vol. ii. chap. xxxviii. which as to details is of different kinds, and produced in different ways in different species. To develop "beauty and singularity of plumage" is a character of the group, but not of any one definite kind, to be explained merely by inheritance. Again, we have the very curious horned flies,1 which agree indeed in a common peculiarity, but in one singularly different in detail in different species, and not known to have any protecting effect. Amongst plants also we meet with similar resemblances. The great group of Orchids includes species which exhibit strange and bizarre approximations to different animal forms, and which have often the appearance of cases of mimicry, as it were in an incipient stage. The number of similar instances which could be brought forward from amongst animals and plants is very great, but the examples given are, it is hoped, amply sufficient to point towards the conclusion which other facts will establish, viz. that there are causes operating (in the evocation of these harmonious diverging resemblances) other than "Natural Selection," or heredity, and other even than merely geographical, climatal, or any simply external conditions. Many cases have been adduced of striking likenesses between different animals, not due to inheritance; but this should be the less surprising, in that the very same individual presents us with likenesses between different parts of its body (e.g. between the several joints of the backbone), which are certainly not explicable by inheritance. This, however, leads to a rather large subject, which will be treated of in the eighth chapter of the present work. 1 Loc. cit. p. 314. Here it will be enough to affirm (leaving the proof of the assertion till later) that parts are often homologous which have no direct genetic relationship-a fact which harmonizes well with the other facts here given, but which “Natural Selection," pure and simple, seems unable to explain. But surely the independent appearance of similar organic forms is what we might expect, a priori, from the independent appearance of similar inorganic ones. As Mr. G. H. Lewes well observes: 1 "We do not suppose the carbonates and phosphates found in various parts of the globe—we do not suppose that the families of alkaloids and salts have any nearer kinship than that which consists in the similarity of their elements, and the conditions of their combination. Hence, in organisms, as in salts, morphological identity may be due to a community of causal connexion, rather than community of descent." "Mr. Darwin justly holds it to be incredible that individuals identically the same should have been produced through Natural Selection from parents specifically distinct; but he will not deny that identical forms may issue from parents genetically distinct, when these parent forms and the conditions of production are identical. To deny this would be to deny the law of causation." Professor Huxley has, however, suggested 2 that such mineral identity may be explained by applying also to minerals a law of descent; that is, by considering such similar forms as the descendants of atoms which inhabited one special part of the primitive nebular cosmos, each considerable space of which may be supposed to have been under the influence of somewhat different conditions. 1 Fortnightly Review, New Series, vol. iii. (April 1868), p. 372. |