180 Sex-limited Inheritance [CH 



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

 The gametes are B$ 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 



The matings are then as follows. 



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

 composition bb $ $ x BB $ 



F! black-eyed hens black-eyed cocks 



Bb $ $ Bb$ $ 



2. Black-eyed $ x Cinnamon pink-eyed $ 

 composition Bb $ $ bb $ $ 



gametes 



pink-eyed hens black-eyed cocks 



o* 



Pink -eyed $ x black-eyed F\ <$ 



composition bb $ $ Bb $ $ 



black-eyed hens black-eyed cocks 



result ^ ?<? b $* 



pink-eyed hens pink-eyed cocks 



bb ? $ bb $ 



Black-eyed $ x black-eyed F^ 



composition Bb $ $ Bb $ $ 



gametes 



black-eyed hens black-eyed cocks 



pink-eyed hens and also 



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 

 disturbing effects of some other dominant factor unde- 

 termined, which alters the normal distribution of the factors 

 B and $ in the gametogenesis of certain black-eyed hens, 

 but that is mere conjecture. 



