"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.] CHAPTER XI THE SPECIAL COLOURS OF PLANTS: THEIR ORIGIN AND PURPOSE The general colour relations of plants--Colours of fruits--The meaning of nuts--Edible or attractive fruits--The colours of flowers--Modes of securing cross-fertilisation--The interpretation of the facts--Summary of additional facts bearing on insect fertilisation--Fertilisation of flowers by birds--Self-fertilisation of flowers--Difficulties and contradictions--Intercrossing not necessarily advantageous--Supposed evil results of close interbreeding--How the struggle for existence acts among flowers--Flowers the product of insect agency--Concluding remarks on colour in nature. The colours of plants are both less definite and less complex than are those of animals, and their interpretation on the principle of utility is, on the whole, more direct and more easy. Yet here, too, we find that in our investigation of the uses of the various colours of fruits and flowers, we are introduced to some of the most obscure recesses of nature's workshop, and are confronted with problems of the deepest interest and of the utmost complexity.