SEXUAL SELECTION. 261 



in any external character; nevertheless, in certain domesti- 

 cated breeds the male is colored differently from the female.* 

 The wattle in the English carrier pigeon and the crop in the 

 Pouter are more highly developed in the male than in the 

 female; and although these characters have been gained 

 through long-continued selection by man, the slight differ- 

 ences between the sexes are wholly due to the form of 

 inheritance which has prevailed; for they have arisen, not 

 from, but rather in opposition to, the wish of the breeder. 



Most of our domestic races have been formed by the 

 accumulation of many slight variations; and as some of the 

 successive steps have been transmitted to one sex alone, and 

 some to both sexes, we find in the different breeds of the 

 same species all gradations between great sexual dissimilar- 

 ity and complete similarity. Instances have already been 

 given with the breeds of the fowl and pigeon, and under 

 nature analogous cases are common. With animals under 

 domestication, but whether in nature I will not venture to 

 say, one sex may lose characters proper to it, and may thus 

 come somewhat to resemble the opposite sex; for instance, 

 the males of some breeds of the fowl have lost their mascu- 

 line tail-plumes and hackles. On the other hand, the dif- 

 ferences between the sexes may be increased under domesti- 

 cation, as with merino sheep, in which the ewes have lost 

 their horns. Again, characters proper to one sex may sud- 

 denly appear in the other sex; as in those sub-breeds of the 

 fowl in which the hens acquire spurs while young; or, as in 

 certain Polish sub-breeds, in which the females, as there is 

 reason to believe, originally acquired a crest, and subse- 

 quently transferred it to the males. All these cases are 

 intelligible on the hypothesis of pangenesis; for they depend 

 on the gemmules of certain parts, although present in both 

 sexes, becoming, through the influence of domestication, 

 either dormant or developed in either sex. 



There is one difficult question which it will be convenient 

 to defer to a future chapter ; namely, whether a character 

 at first developed in both sexes could through selection be 

 limited in its development to one sex alone. If, for 

 instance, a breeder observed that some of his pigeons (of 



* Dr. Chapuis, " Le Pigeon Voyageur Beige," 1865, p. 87. Boitard 

 et Corbie, " Les Pigeons do Voliere," etc., 1824, p. 173. See, also, 

 on similar differences in certain breeds at Modena, " Le variazioni del 

 Colouibi domestic!," del Paolo Bonizzi, 1878. 



