:o6 



MENDELISM 



CHAP. 



passed for unpigmented birds, for with the exception 

 of an occasional fleck of pigment their skin, comb, 



, and wattles were as clear 



Silky 

 ? 



Brown Leghorn 



x 6 



? x S 



F, 



4 <$ <S f ? ? $---f 2 



Fig. 19. 



as in the Brown Leghorn 

 (PL V., 1 and 4). Dissec- 

 tion revealed the presence 

 of a slight amount of 

 internal pigment. Such 

 birds bred together gave 

 some offspring with the 



Scheme illustrating the result of crossing a 

 Silky hen with a Brown Leghorn cock, full pigmentation of the 

 Black sex signs denote deeply pigmented 



birds, and light sex signs those without pig- Silky, SOme Without any 

 mentation. The light signs with a black dot 



in the centre denote birds with a small pigment, and Others sh0W- 

 amount of pigment. . 



ing different degrees 01 

 pigment. None of the F 2 male birds, however, showed 

 the full deep pigmentation of the Silky. 



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

 viz. Brown Leghorn hen X Silky cock, the result was 

 different. While the 



Fi male birds were 

 almost destitute of 

 pigment as in the 

 previous cross, the 

 Fi hens, on the other 

 hand, were nearly 

 as deeply pigmented 

 as the pure Silky 



Brown Leghorn 



9 x 



Silky 





--F. 



rf<?G?0*¥??$ 



Fig. 20. 

 Scheme illustrating the result of crossing a Brown Leg- 

 horn hen with a Silky cock (cf. Fig. 19). 



