136 



HEREDITY AND SEX 



if present, some inhibitory factor must bring about sup- 

 pression of the horns. The former assumption seems 

 more probable, for, as I shall point out, certain experi- 

 ments in heredity indicate that no inhibitor is present 

 in hornless breeds. 



The series is completed by cases like that of 

 the eland and the reindeer. Both males and females 



tfi 



■1:>.. ■ ^t 



Fig. 69. — Fat-tailed hornless sheep (Ovis 

 aries steatopyga persicci). 



have well-developed horns. In this case the hereditary 

 factors suffice in themselves for the complete develop- 

 ment of horns, for even after castration the horns de- 

 velop. 



We have anticipated to some extent the conclusions 

 arrived at by breeding experiments in these races of 

 sheep. The best-known case is that of Wood, who 

 crossed horned Dorsets and hornless Suffolks. As 



