Chap. VIII. SEXUAL SELECTION. 283 



tion ; but a few instances may here be given. There 

 are breeds of the sheep and goat, in which the horns 

 of the male differ greatly in shape from those of the 

 female ; and these differences, acquired under domes- 

 tication, are regularly transmitted to the same sex. 

 With tortoise-shell cats the females alone, as a general 

 rule, are thus coloured, the males being rusty-red. 

 With most breeds of the fowl, the characters proper 

 to each sex are transmitted to the same sex alone. So 

 general is this form of transmission that it is an ano- 

 maly when we see in certain breeds variations trans- 

 mitted equally to both sexes. There are also certain 

 sub-breeds of the fowl in which the males can hardly 

 be distinguished from each other, whilst the females 

 differ considerably in colour. With the pigeon the 

 sexes of the parent-species do not differ in any external 

 character; nevertheless in certain domesticated breeds 

 the male is differently coloured from the female. 22 

 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 difference between the two sexes is wholly due to 

 the form of inheritance which has prevailed ; for it 

 has arisen, not from, but rather in opposition to, the 

 wishes 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 diffe- 

 rent breeds of the same species all gradations between 

 great sexual dissimilarity and complete similarity. In- 



32 Dr. Cliapuis, ' Le Pigeon Voyageur Beige,' 1865, p. 87. Boitard 

 et Corbie, « Les Pigeons de Voliere,' &c, 1824, p. 173. 



