144 HEREDITY AM) SEX 



of the secondary sexual characters of the domestic 

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

 \ male Seabright was mated to a black-breasted game 

 female. The son was hen-feathered and like the Sea- 

 brighl father in this respect. Evidently in this case 

 the secondary sexual character in question is dominant 

 and is transmitted from father to son. 



In the reciprocal cross one hen was obtained which 

 was back-crossed to a recessive male. She produced 

 both hen-feathered and normally feathered sons. The 

 character appears therefore to be sex-limited but not 

 sex-linked. If hen-feathering in the Seabright be rep- 

 M'-ented by S and its normal allelomorph by s, the 

 first cross would be as follows : — 



Game $ sF — s 



Seabright S S — S 



F 1 



SsF female 



Ss hen-feathered male 



Eggs of Fi SF~sF--S 



Sperm of F x S — s 



F 2 Females F 2 Males 



SSF SS hen-feathered 



SsF Ss hen-feathered 



sSF sS hen-feathered 



ssF ss cock-feathered 



In conclusion, then, in mammals the secondary sexual 

 characters owe their development to the testes. The 

 testes add something to the common inheritance. 

 Bui in birds the ovary takes something away. 



