180 Sex-limited Inheritance [en. 



The allelomorphs are 



?, $, presence and absence of femalencss. 



B, b, 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 13$ and <$$. 



The pure black-eyed green male is pure in maleness 

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

 composition is represented thus $$B. 



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 $ 



(B$ alUcT 



gametes |, 



FI pink-eyed hens black-eyed cocks 



bb* c? Bb& $ 



3. Pink-eyed * x black-eyed F^ $ 

 composition bb $ $ Bb $ $ 



(black-eyed hens black-eyed cocks 



result W* Bb ** 



\pink-eyed hens pink-eyed cocks 



4. Black-eyed ? x black-eyed F l 



composition Bb ? <J Bb $ $ 



sametes f/ 



I black-eyed hens black-eyed cocks 



Bb*& BBt 



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 



