90 MENDELISM chap. 



Brown Leghorn (PI. VI., i and 4). Dissection 

 revealed the presence of a slight amount of internal 

 pigment. Such birds bred together gave some off- 

 spring with the full pigmentation of the Silky, some 

 without any pigment, and others showing different 

 degrees of pigment. None of the F^ male birds, 

 however, showed the full deep pigmentation of the 

 Silkv. 



When, however, the cross was made the other way, 



viz. Brown Leg- 

 Brown Leghorn ^ SUky ^^^^ hen X Silky 



cock, the result 

 was different. 

 While the F, male 

 birds were almost 

 destitute of pig- 

 ment as in the 

 Fig. 20. previous cross, the 



Scheme illustrating the result of crossing a Brown E henS, On the 

 Leghorn hen with a Silky cock (cf. Fig. 19). * 



Other hand, were 

 nearly as deeply pigmented as the pure Silky (PI. VI., 

 2). The male Silky transmitted the pigmentation, 

 but only to his daughters. Such birds bred together 

 gave an F^ generation containing chicks with the full 

 deep pigment, chicks without pigment, and chicks 

 with various grades of pigmentation, all the different 

 kinds in both sexes. 



In analysing this complicated case many other 

 different crosses were made, but for the present it 

 will be sufficient to mention but one of these, viz. 

 that between the F^ birds and the pure Brown 

 Leghorn. The cross between the F^ hen and the 

 Brown Leghorn cock produced only birds with a 



