The Evidence from Sexual Characters. 225 



These extracts are sufficient to show that organs which 

 are confined to the cock are especially variable, and that 

 the characteristics of each breed are chiefly modifications 

 of their male parts. 



It is therefore evident that the males of the various 

 breeds are as a rule much more different from each other 

 than the females, in fowls, as well as in sheep, pigeons 

 and other domestic animals. The rule is by no means 

 universal, however, and there are a few remarkable ex- 

 ceptions. I have already mentioned two cases of black- 

 breasted red game fowls, in which the females were 

 quite distinct, while the males of the two forms could 

 not be distinguished. The breed of domestic ducks 

 known as the Call Duck is remarkable for its small size 

 and from the extraordinary loquacity of the female, 

 while the drake only hisses like ordinary drakes. 



Darwin gives ( Variation, Vol. I. p. 309) an interest- 

 ing account of the origin of the crest in Polish fowls. 

 He says that in most fowls head ornaments of all kinds 

 are more fully developed in the male than in the female; 

 but in Polish fowls the crest or top-knot, which in the 

 male replaces the comb, is equally developed in both 

 sexes. "In certain sub-breeds, which from the hen 

 having a small crest are called lark-crested, a single up- 

 right comb sometimes almost entirely takes the place of 

 the crest in the male. From this latter case, and from 

 some facts presently to be given with respect to the pro- 

 tuberance of the skull in Polish fowls, the crest in this 

 breed ought perhaps to be viewed as a feminine charac- 

 ter which has been transferred to the male. ... At the 

 present day all the breeds of Polish fowls have the great 

 bony protuberance on their skulls, which includes part 

 of the brain and supports the crest, equally developed 

 in both sexes. But formerly in Germany the skull of 



