DED UCTION. ANTICIPA TION. 1 5 3 



Darwin had concluded that characters inherited 

 by both sexes appear early in life, and that char- 

 acters restricted to one sex appear late. He 

 said, " I was led to infer that a relation of this 

 kind exists, from the fact that whenever and in 

 whatever manner the adult male has come to 

 differ from the adult female, he differs in the 

 same manner from the young of both sexes." 

 This induction he proceeded to strengthen by 

 deduction at both ends. He deduced the law 

 from a still more general one, as follows : " It 

 is in itself probable that any character appear- 

 ing at an early age would tend to be inherited 

 equally by both sexes, for the sexes do not 

 differ much in constitution, before the power 

 of reproduction is gained " ; and in the same 

 way characters appearing late in one sex would 

 tend to be restricted to that sex. l 



From the other side, he sought to test the 

 law by an examination of its consequences; and 

 chose the deer family as a crucial instance, upon 

 which he felt he could rely. 2 In some species 

 of this family the males alone have horns, and 

 in one species both sexes have them. If the 

 law were true, horns should appear late in 

 the species in which they are restricted to the 



1 Descent of Man, etc., Vol. I. p. 276. 



2 Ibid., p. 278 et seq. 



