240' EVOLUTION, GENETICS, AND EUGENICS 



ing around, like Indians in a war-dance, for the possession of the 

 females; male salmons have been observed fighting all day long; male 

 stag-beetles sometimes bear wounds from the huge mandibles of other 

 males; the males of certain hymenopterous insects have been fre- 

 quently seen by that inimitable observer M. Fabre, fighting for a 

 particular female who sits by, an apparently unconcerned beholder 

 of the struggle, and then retires with the conqueror. The war is, 

 perhaps, severest between the males of polygamous animals, and 

 these seem oftenest provided with special weapons. The males of 

 carnivorous animals are already well armed; though to them and to 

 others, special means of defense may be given through means of 

 sexual selection, as the mane of the lion, and the hooked jaw to the 

 male salmon; for the shield may be as important for victory as the 

 sword or spear. 



Amongst birds, the contest is often of a more peaceful character. 

 All those who have attended to the subject believe that there is the 

 severest rivalry between the males of many species to attract, by 

 singing, the females. The rock-thrush of Guiana, birds of paradise, 

 and some others, congregate; and successive males display with the 

 most elaborate care, and show off m the best manner, their gorgeous 

 plumage; they likewise perform strange antics before the females, 

 which, standing by as spectators, at last choose the most attractive 

 partner. Those who have closely attended to birds in confinement 

 well know that they often take individual preferences and dislikes: 

 thus Sir R. Heron has described how a pied peacock was eminently 

 attractive to all his hen birds. I cannot here enter on the necessary 

 details; but if man can in a short time give beauty and an elegant 

 carriage to his bantams, according to his standard of beauty, I can 

 see no good reason to doubt that female birds, by selecting, during 

 thousands of generations, the most melodious or beautiful males, 

 according to their standard of beauty, might produce a marked effect. 

 Some well-known laws, with respect to the plumage of male and 

 female birds, in comparison with the plumage of the young, can partly 

 be explained through the action of sexual selection on variations 

 occurring at diflferent ages, and transmitted to the males alone or to 

 both sexes at corresponding ages; but I have not space here to enter 

 on this subject. 



Thus it is, as I beheve, that when the males and females of any 

 animal have the same general habits of life, but differ in structure, 

 color, or ornament, such differences have been mainly caused by sexual 



