280 



Genetic Studies in Poultry 



with that delicacy of appearance so often characteristic of the highly 

 inbred thing. On being crossed with the Langshan (/ the chicks left 

 nothing to be desired from the point of view of health and vigour. The 

 black down of the Langshan proved to be dominant over that of the 

 brown stripe of the Leghorn, and a simple 3 : 1 ratio was realised in F^. 

 In adult plumage the F^ hens were full black with dark eyes and 

 shanks; the F^ cocks were, on the whole, black with a varying amount of 

 orange in the neck, shoulder and saddle hackles: the eye was orange 

 and the shanks were horn on light. The sexual differences in the last 

 I two characters are doubtless due to a sex-linked inhibitor introduced 

 \ by the Brown Leghorn hen. The eggs laid by the F^ birds were tinted, 

 though rather lightly, approximating to grades 4 and 5\ In 1911-12 

 a number of jPs ? ? "^ were reared, and 65 were subsequently tested in 

 respect of egg-colour. The results are shown schematically in Fig. 1. 

 The range is from white up to grade 10, i.e. almost as deep as the 

 Langshan's eggs. The great majority however laid white or light- 

 tinted eggs. 



it 



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Fig. 1. Distribution of grades of egg-colour in F2 generation ex Brown Leghorn 



<J X Langshan ^ , 



Before passing on to the Hamburgh-Langshan cross, a further 

 experiment with the Brown Leghorn and Langshan calls for attention. 

 In 1912 we made the cross reciprocal to that described above, mating 

 a Brown Leghorn cf with a Langshan % . The Leghorn </* was purchased, 



1 This statement is from recollection. The original records of the Fi birds were in the 

 keeping of my colleague. In the turmoil of war they appear to have gone astray, and 

 I was unable to trace them among his papers after he had been killed. [R. C. P.] 



^ 3 Fx (f <? and 12 Fj ? $ in all were used for producing the F^ generation. 



