238 Genetic Studies in Poultry 



(1) Chamois (/ x Brown Leghorn $. The seven chicks hatched from 

 this mating were all light in down with a slight huffish tinge. The 

 result accords with the view that Chamois acts as a dominant white, 

 and that the cock used was homozygous in this respect. Of the seven 

 chicks one only was reared, and proved to be a white cockerel with a good 

 deal of gold irregularly distributed over its plumage. Here and there 

 slight indications of barring were present. 



(2) Chamois % x Gold Campine cf. Of 21 chicks produced 14 proved 

 to be chamois, and the remaining seven gold barred. Both sexes appeared 

 in each colour class. From this, and from other evidence, we regard 

 chamois as dominant to gold barred, the chamois $ used here being 

 heterozygous. 



(3) Chamois $ x Silver Campine (/. In this experiment the same 

 chamois ^ was used as in (2). As to be expected she gave chicks with 

 light and with coloured downs in approximately equal numbers, viz. 

 17 light and 15 dark. Of the chicks with dark down those reared (1 </ 

 and 3 $ $ ) all developed into silver barred birds. Four also of the chicks 

 with light down were reared. All proved to be males, and all developed 

 into white birds. 



(4) Chamois cf x Silver Campine $. The cock here was the same 

 bird as that used in (1), and it was to be expected therefore that all of 

 the chicks would be light in the down. Such was the case. But although 

 the downs were all light they fell into two distinct classes, viz. those 

 which were light with a slight huffish tinge, and those which were 

 mottled with buff. Of the 24 chicks hatched 12 belonged to each class. 

 Three of those with buff mottled down^ were reared and turned out to 

 be all pullets, while the eight with light down reared all developed into 

 white cockerels. 



These last two experiments shew that it is possible to produce white 

 birds from a cross between two coloured varieties, each of which breeds 

 true to its own colour. Corresponding feathers from a Silver Campine (a), 

 a Chamois (c), and a white (6) resulting from a cross between the two are 

 shewn in Fig. 1. 



We offer the following interpretation. The silver differs from the 

 gold in the possession of a factor which inhibits the production of the 

 gold pigment without affecting the black. This factor is sex-linked in 

 its mode of transmission. The Chamois differs from the gold in the 

 possession of a factor which inhibits the production of the dark melanic 

 pigment, but appears to have little or no influence on the gold pigment. 

 ^ This is the down characteristic of the Chamois Campine. 



