Page:Popular Science Monthly Volume 83.djvu/536

532 variable as color, that, therefore, concealment is most easily obtained by color modification. Protective resemblance in all its manifold forms has ever been dominant in his mind as a greater principle than that of the sexual selection of color which Darwin favored.

Here may be cited Wallace's own account of his famous observation of mimicry in the loaf butterfly from his volume of 1869, "The Malay Archipelago":

In 1867, in a manner which delighted Darwin, Wallace advanced his provisional solution of the cause of the gay and even gaudy colors of caterpillars as warnings of distastefulness. In 1868 he propounded his explanation of the colors of nesting birds, that when both sexes are conspicuously colored, the nest conceals the sitting bird, but when the male is conspicuously colored and the nest is open to view, the female is plainly colored and inconspicuous. His theory of recognition colors as of importance in enabling the young of birds and mammals to find their parents was set forth in 1878, and he came to regard it as of very great importance.

In "Tropical Nature" (1878) the whole subject of the colors of animals in relation to natural and sexual selection is reviewed, and the general principle is brought out that the exquisite beauty and variety of insect colors has not been developed through their own visual perceptions, but mainly and perhaps exclusively through those of the higher animals which prey upon them. This conception of color origin, rather than that of the general influence of solar light and heat or the special action of any form of environment, leads him. to his functional and biological classification of the colors of living organisms into five groups, which forms the foundation of the modern more extensive and critical classification of Poulton. He concluded (p. 172):