PAIRS OF CHARACTERS 125 



the two members of a pair of characters is the domi- 

 nant. When, for instance, one of the members of 

 a pair of characters is that borne by the species 

 in which the character occurs in its wild state, and 

 the other only occurs in a state of domestication, it 

 would be supposed, according to this theory, that 

 the " wild " character, being the older, would be the 

 dominant, and the " domesticated " one, being the 

 more recent, would be the recessive. In mice, for 

 instance, the grey of the house mouse would be 

 expected to be — and is — dominant over the white 

 of the albino. Now, there are a great number of 

 cases which support this theory. For instance, the 

 dominant members of the pairs of characters pre- 

 sented by the cotyledons in Pisum — yellow and 

 round — both occur in the wild specimens of the 

 wild Pisum which have been examined. There are, 

 however, a number of cases in which this theory 

 breaks down entirely. For instance, the single comb 

 in the domestic fowl, which is known to be the form 

 of the comb in the wild ancestral stock of the jungle, 

 is recessive to the " rose " and to the " pea " comb. 

 The absence of a tail in rumpless breeds of fowl is 

 dominant to the ordinary tailed condition which 

 characterises the majority of domestic breeds, and, 

 of course, the wild representatives of the species. 

 So this theory falls to the ground. 



We see, therefore, that though many characters 

 of wild species are dominant to their domesticated 

 counterparts, the fact that certain of them are not 

 dominant suggests that, in those cases where they 



