Chap. XV. SEXUALLY-LIMITED INHERITANCE. 159 



success lias quickly followed the order. Now the lop- 

 ping of the comb must be sexually limited in its trans- 

 mission, otherwise it would prevent the comb of the 

 male from being perfectly upright, which would be 

 abhorrent to every fancier. On the other hand the 

 uprightness of the comb in the male must likewise be 

 a sexually-limited character, otherwise it would prevent 

 the comb of the female from lopping over. 



From the foregoing illustrations, we see that even 

 with almost unlimited time at command, it would be 

 an extremely difficult and complex process, though 

 perhaps not impossible, to change through selection 

 one form of transmission into the other. Therefore, 

 without distinct evidence in each case, I am unwilling 

 to admit that this has often been effected with natural 

 species. On the other hand by means of successive 

 variations, which were from the first sexually limited 

 in their transmission, there would not be the least 

 difficulty in rendering a male bird widely different in 

 colour or in any other character from the female ; the 

 latter being left unaltered, or slightly altered, or specially 

 modified for the sake of protection. 



As bright colours are of service to the males in their 

 rivalry with other males, such colours would be selected, 

 whether or not they were transmitted exclusively to the 

 same sex. Consequently the females might be expected 

 often to partake of the brightness of the males to a 

 greater or less degree ; and this occurs with a host of 

 species. If all the successive variations were trans- 

 mitted equally to both sexes, tlie females would be 

 undistinguishable from the males ; and this likewise 

 occurs with many birds. If, however, dull colours were 

 of high importance for the safety of the female during 

 incubation, as with many ground birds, the females 

 which varied in brightness, or which received through 



