46 Genetic Studies in Poultry 



zygous bird may be fully henny, and among the fully henny heterozygous 

 birds that we have bred we have had some which in colour, as well as in 

 feather structure, closely matched the corresponding hen. The hetero- 

 zygous Silver-Pencilled Hamburgh, figured on PI. IX, offers a good 

 example of this. Again, among the fully henny F2 heterozygous birds 

 that we bred, ex Sebright x Hamburgh, we had examples of silver-laced 

 and of gold-pencilled birds which were henny in colour and pattern as 

 well as in feather. When we introduced the Brown Leghorn we obtained 

 some dark mossed cocks which corresponded exactly in colour to hens 

 similarly bred. The feathers of these birds were very like those of 

 ^ 201/14, figured on PI. VIII, figs. 2 and 4. From their dark eyes and 

 the purplish tinge in the face we have little doubt that, as compared 

 with a Black-red, they contained some obscuring factor operating for 

 the increased production of melanic pigment. This is further borne 

 out by the down colour of such birds, which was dark blackish-brown, 

 a colour known to be dominant to brown stripe. The henny Silver 

 Wyandotte figured by Lamon and Slocum (p. 105) is evidently like 

 a hen in colour and pattern, and as these birds are uncommon it is 

 extremely likely that he was heterozygous. We are inclined therefore 

 to consider that in our first group the heterozygous bird, if fully henny 

 in feather structure, resembles the hen also in colour. 



We doubt however whether this applies to the birds of our second 

 group, where sexual differences occur in colour apart from the sexual 

 feathers. In order to try and throw light on this point we attempted to 

 " hennify " the Brown Leghorn by repeated crosses of heterozygous cocks 

 with Brown Leghorn hens. The nature of the experiment is summarised 

 in the accompanying scheme : 



n Leghorn 9 j 



Brown Leghorn 9 



Brown Leghorn J 1 ^ ^ 240/13, 309/13 



(J 286/14 

 (henny) 



[Exp. 16] 1- ^ 242/16 



9 Brown Leghorn ) (henny) 



[Exp. 19] f ^ 338/17 



9 Brown Leghorn I (henny) 



In this series of matings our procedure was to choose fi:-om our 

 available birds the cock that was nearest to a black-red, and mate each 

 time with a Brown Leghorn. (^ 286 x Brown Leghorn % gave chicks 

 with two types of down, viz. dark black-brown and brown stripe in 

 almost equal numbers. Of the brown-striped </ 242 resembled a Brown 

 Leghorn in juvenile plumage, subsequently becoming a henny. The 



