144 HEREDITY AND SEX 



of the secondary sexual characters of the domestic 

 races, notably the saddle feathers, as shown in Fig. 73. 



When a female Seabright was mated to a black- 

 breasted game male the sons had the secondary sexual 

 plumage of the father. 



In the second generation, however, some of the males 

 showed imperfect development of the sickle feathers 

 to various degrees — some to the extent shown by the 

 Seabright. It appears that the female transmits the 

 features peculiar to the male of this race. 



In conclusion, then, in mammals the secondary sexual 

 characters owe their development to the testes. The 

 testes add something to the common inheritance. 

 But in birds the ovary takes something away. 



