108 Heredity, 



sex, in a latent condition, of the organization of tlie 

 other sex ; but it is not difficnlt to show that the phenom- 

 ena in question admit of a much simpler explanation. 



In most cases when the sexes differ from each other in 

 what are known as secondary sexual characteristics, that 

 is, features which are not directly concerned in the re- 

 productive function, the mature male is more different 

 than the mature female from the young. I shall discuss 

 this subject more fully in another place, so I shall give 

 only a few illustrations at present. It will be sufficient 

 to call attention to the resemblance between the smooth 

 face of a woman and the face of either a boy or a girl, 

 as contrasted with the bearded face of a man. The 

 voice of a woman, the voice of a girl, and that of a boy, 

 all resemble each other, and all differ from the voice of 

 a man in the same, or nearly the same, respects. 



In fowls the young of both sexes are much like the 

 adult female in form and color. 



These familiar instances are enough for our present 

 purpose, and they show that, so far as the secondary 

 sexual characteristics are concerned, the female is, as a 

 rule, distinguished from the male by her failure to 

 acquire the fully developed characteristics of the race. 

 In these respects the female is an arrested male, and 

 this is well shown by that fact that while the females 

 and young of two closely related species of wild animals 

 may be so much alike that they can hardly be distin- 

 guished, the adult males may be Ycry different from 

 each other. 



All we need to assume, then, in order to reach a sim- 

 ple explanation of the secondary sexual differences be- 

 tween the sexes, is that each ovum has the power to 

 develop into an organism with all the characteristics of 

 the sj^ecies, but that the female function acts, in some 



