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THE problems connected with the origin and uses of the colors of animals and the songs of birds have been a fascinating and puzzling subject of research and speculation from the beginning of evolutionary science, and perhaps will remain unsolved to the end of zo6logical inquiry. There has been a marked tendency of late to set up theories opposed-at least on their faces-to the Darwinian theory of sexual selection. Some of these new theories postulate rivalry and even antagonism as the keynote to the evolution of bright color, display, and bird-song. One of these is set forth in an interesting and suggestive book by Major R. W. G. Hingston,l an Englishman who has had a considerable field experience in India and South America in the observation of mammals, birds, and insects and who has read rather widely, though apparently without giving much attention to recent American authors. Another is outlined in Dr. Arthur A. Allen's recent paper on 'Sex Rhythm in the Ruffed Grouse (Bonawa umbellm Linn.) and Other Birds.'2 It seems worth while to examine both of these theories rather carefully, and though they are by no means identical, they have enough in common to warrant considering them in a single paper. I shall take up Major Hingston's book first because it was the first to appear, and I shall discuss some of the broader aspects of the general subject before taking up Dr. Allen's paper. To give the substance of his book in very brief form, it may be said that Hingston attributes all conspicuous color and all conspicuous appendages, such as horns, crests, manes, and tufts of hair or feathers, to a need for their use in combat. He shows that animals in fighting erect their crests, elevate their tails, spread their manes, and otherwise make themselves as large and conspicuous as possible, and he argues, with some show of reason,

The Rôle of Anger in Evolution with Particular Reference to the Colors and Songs of Birds