THE THEORY OF COURTSHIP 149 



the whole body of the male is fairly converted into a 

 musical instrument, being immensely inflated, hollow, 

 and distended like a pellucid air-bladder in order to act 

 as an efficient sounding-board. Among the beetles, 

 taste seems generally to have specialised itself rather 

 on form than on music or colour, and the males are 

 here usually remarkable for their singular and very 

 complicated horns, often compared in various species to 

 those of stags or rhinoceroses, and entirely absent in 

 the females of most kinds. But it is among the butter- 

 flies and moths that insect sestheticism has produced its 

 greatest artistic triumphs ; for here the beautiful eye- 

 spots and delicate markings on the expanded wing- 

 membranes are almost certainly due to sexual selection. 

 The higher animals display like evidence of the same 

 slow selective action. The courtship of the stickleback, 

 who dances ' mad with delight ' around the mate he has 

 allured into the nest he prepares for her, has been ob- 

 served by dozens of observers both before and since in 

 the domestic aquarium. The gem-like colours of the 

 male dragonet, the butterfly wings of certain gurnards, 

 and the decorated tails of some exotic carps all point in 

 the same direction. Our own larger newt is adorned 

 during the breeding season with a serrated crest edged 

 with orange ; while in the smaller kind the colours of 

 the body acquire at the same critical period of love- 

 making a vivid brilliancy. The strange horns and 

 luridly coloured throat-pouches of tropical lizards are 

 familiar to all visitors in equatorial climates, and they 

 are confined exclusively to the male sex. Among birds, 

 the superior beauty of the male plumage is known to 

 everybody ; and their greatest glory invariably coincides 

 14 



