io6 



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 Crown Leghorn 



f X J 



r^ 

 ? 



i <s s 



^ 



-F, 



? ? $---F. 



as in the Brown Leghorn 

 (PL v., I and 4). Dissec- 

 tion revealed the presence 

 of a slight amount of 

 internal pigment. Such 

 birds bred together gave 

 some offspring with the 



Fig. 19. 



Scheme UlustratiDg the result of ciossing a 

 Silky hen with a Brown Leghorn coclt. fuU 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 smaU pigment, and OtherS shoW- 

 amoimt of pigment. 



mg different degrees of 

 pigment. None of the F2 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 

 Fj hens, on the other 

 hand, were nearly 

 as deeply pigmented Fi<5- ^o. 



•■ 5j.,, Scheme illustrating the result of crossing a Brown Leg- 



as tne pure OllKy horn hen with a Silky cock (cf. Fig.'ip). 



F, 



