THE HEREDITY OF SEX 47 



Still more striking was the incomplete segregation 

 in the plumage colour. The white of the Silky 

 was recessive, all the birds of the F^ generation 

 being fully coloured. In the Fo generation there 

 were two recessive white cocks which when mature 

 showed slight yellow colour across the loins. These 

 two were mated with coloured hens, and in later 

 generations all the recessives instead of being pure 

 white, like the Silky, had reddish-brown pigment 

 distributed as in pile fowls. In the hens (Plate i., 

 fig. 1) it was chiefly confined to the breast and 

 abdomen, and was well developed, not a mere tinge 

 or trace, but a deep coloration, extending on to the 

 dorsal coverts at the lower edge of the folded wings. 

 The back and tail were white. In the cocks the 

 colour was much paler, and extended over the 

 dorsal surface of the wings, where it was darker 

 than on the back and loins (Plate i., fig. 2). These 

 pile-coloured fowls when mated together bred true, 

 with individual differences in the offspring. 



The pile fowl as recognised and described by 

 fanciers is dominant in colour, not recessive as in 

 the case above described. In fact, a recessive 

 pile does not appear ever to have been mentioned 

 before the publication of the results of my experi- 

 ment. From the statements of John Douglas in 

 Wrighfs Book of Poultry (London, 1885), it appears 

 that fanciers knew long ago that the pile could be 

 produced from a female of the black-red Game 

 mated with a white Game-cock. It would seem, 

 therefore, that the pile is the heterozygote of black- 

 red and ' dominant ' white. Bateson, however 

 (Principles of Heredity, 1909, p. 120), writes that 

 the whole problem of the pile is very obscure, and 



