158 SEXUAL SELECTION : BIRDS. Part IL 



not all, of tlie successive steps might be transferred to 

 both sexes, and the female would then closely resemble 

 the male. There can hardlv be a doubt that this is 

 the cause of the male pouter pigeon haying a somewhat 

 larger crop, and of the male carrier pigeon having some- 

 what larger wattles, than their respective females ; for 

 fanciers have not selected one sex more than the other, 

 and have had no wish that these characters should be 

 more strongly displayed in the male than in the female, 

 yet this is the case with both breeds. 



The same process would have to be followed, and the 

 same difficulties would be encountered, if it were desired 

 to make a breed with the females alone of some uew 

 colour. 



Lastly, our fancier might wish to make a breed with 

 the two sexes differing from each other, and both from 

 the parent-species. Here the difficulty would be ex- 

 treme, unless the successive variations were from the 

 tirst sexually limited on both sides, and then there would 

 be no difficulty. We see this with the fowl ; thus the 

 two sexes of the pencilled Hamburghs differ greatly 

 from each other, and from the two sexes of the abori- 

 ginal Gallus hanhiva ; and both are now kept constant 

 to their standard of excellence by continued selection, 

 which would be impossible unless the distinctive charac- 

 ters of both were limited in their transmission. The 

 Spanish fowl offers a more curious case ; the male has 

 an immense comb, but some of the successive variations, 

 by the accumulation of which it was acquired, appear 

 to have been transferred to the female ; for she has a 

 comb many times larger than that of the females of the 

 parent-species. But the comb of the female differs in 

 one respect from that of the male, for it is apt to. lop 

 over; and within a recent period it has been ordered 

 by the fancy that this should always be the case, and 



