i8o Sex-limited Inheritance [en. 



The allelomorphs are 



?, ^, presence and absence of femaleness. 



B, by presence and absence of the factor for black eye 



The '"pure" green hen is thus %$Bb, being, as experi- 

 ment proves, actually heterozygous for the black-eye-factor. 

 The gametes are BZ and b%. 



The pure black-eyed green male is pure in maleness 

 (recessive) and in the dominant black-eye-factor, and his 

 composition is represented thus $$BB. 



The Cinnamon hen is '^^bb and the Cinnamon cock is 

 $$bb. 



The matings are then as follows. 



1. Cinnamon pink-eyed $ x black-eyed ^ 

 composition bb^ $ x BB 5 $ 



jFi black-eyed hens black-eyed cocks 



Bb2 3 Bb6 6 



2. Black-eyed ? x Cinnamon pink-eyed S 



This representation is therefore complete except in so 

 far as it takes no account of the production of black-eyed 

 hens together with pink-eyed, which Miss Durham has 

 twice seen in mating (2). These create a definite difficulty 

 which as yet there is no means of overcoming. The con- 

 jecture may be hazarded that they owe their origin to the 



