120 HEREDITY AND SEX 



courtship. It is so inferior to vigor, to the sense of 

 smell and to touch in the lower animals at least, that 

 it is very questionable whether it has had anything 

 more to do with mating than helping the sexes find 

 each other. 



VIGOR AND SECONDARY SEXUAL CHARACTERS 



We have seen that Darwin himself has stated ex- 

 plicitly that unless the secondary sexual characters 

 are associated with greater vigor, or productivity, 

 nothing can be accomplished. 



It will be recalled that Wallace, who disbelieved in 

 Darwin's theory of sexual selection, attempted to ac- 

 count for the appearance of secondary sexual characters 

 on the ground of the greater vigor of the male (he 

 sometimes says vitality and again activity of the male) 

 at the breeding season. The vigor is assumed to be 

 associated with the development of the sex glands 

 at this time. This may be admitted, but whether the 

 vigor is the result of the sex glands, or the sex glands of 

 the vigor, is a nice point that I shall not try to decide. 

 It may appear that Wallace's view is in part justified 

 from the facts that we have examined. But I do not 

 think so. In the first place, he attempts the impos- 

 sible task of explaining the outgrowths and colors that 

 appear in special regions by the local activity of the 

 muscles (for example) in those regions. The facts 

 before us do not support any such interpretation. The 

 Peckhams easily overturn his argument, as applied to 

 spiders. 



Second, in birds, to which Wallace mainly refers, the 

 sex glands of the male do not affect the secondary 



