[129] Coloration in Animals and Plants, London, 1886.
[130] Coloration of Animals, Pl. X, p. 90; and Pls. II, III, and IV, pp. 30, 40, 42.
[131] See coloured Fig. in Proc. Zool. Soc., 1871, p. 626.
[132] A. Tylor's Coloration, p. 40; and Photograph in Hutchinson's Illustrations of Clinical Surgery, quoted by Tylor.
[133] For activity and pugnacity of humming-birds, see Tropical Nature, pp. 130, 213.
[134] Tropical Nature, p. 209. In Chapter V of this work the views here advocated were first set forth, and the reader is referred there for further details.
[135] The Rev. O. Pickard-Cambridge, who has devoted himself to the study of spiders, has kindly sent me the following extract from a letter, written in 1869, in which he states his views on this question:—
"I myself doubt that particular application of the Darwinian theory which attributes male peculiarities of form, structure, colour, and ornament to female appetency or predilection. There is, it seems to me, undoubtedly something in the male organisation of a special, and sexual nature, which, of its own vital force, develops the remarkable male peculiarities so commonly seen, and of no imaginable use to that sex. In as far as these peculiarities show a great vital power, they point out to us the finest and strongest individuals of the sex, and show us which of them would most certainly appropriate to themselves the best and greatest number of females, and leave behind them the strongest and greatest number of progeny. And here would come in, as it appears to me, the proper application of Darwin's theory of Natural Selection; for the possessors of greatest vital power being those most frequently produced and reproduced, the external signs of it would go on developing in an ever-increasing exaggeration, only to be checked where it became really detrimental in some respect or other to the individual."
This passage, giving the independent views of a close observer—one, moreover, who has studied the species of an extensive group of animals both in the field and in the laboratory—very nearly accords with my own conclusions above given; and, so far as the matured opinions of a competent naturalist have any weight, afford them an important support.