Constitution of the White Leghorn Breed. 163 



will be shown later, this is contrary to the established method of 

 inheritance of barring as it occurs in the Barred Plymouth Rock 

 breed; and without more convincing evidence the case does not 

 appear to warrant the assumption that barring of this sort is inherited 

 in any other manner than that now generally accepted. 



IIL Experimental Results. 



As has been stated, at the outset of this investigation barring was 

 tentatively regarded as a heterozygous condition resulting from the 

 mating of black with white fowls. Therefore the preliminary experi- 

 ment involved chiefly the mating of these breeds with the aim of 

 securing from some of the crosses a certain number of individuals 

 possessing the barred color-pattern. These crosses were between the 

 White Leghorn cT and the following black 99: White-faced Black 

 Spanish, Black Minorca, Black Langshan, Black Java, Black Ham- 

 burg and Black Cochin. The Fi generation was bred in 1910. In 

 1911, the Fi breeding was continued and in atldition a number of the 

 F2 generation from some of the crosses were reared. In 1912, a 

 greater number of the F2 generation were reared, and also a number of 

 other crosses were made between selected F2 stock and several other 

 varieties of fowl. It may be said in passing that all the stock used 

 in the experiments was carefully selected from reputable breeders 

 and was probably as pure-bred as any that could be obtained in the 

 country. The breeds mentioned were chosen for the experiments 

 first of all, because so far as could be ascertained from poultry 

 literature none of them was known to be related to breeds possessing 

 the barred color-pattern such as the Barred Plymouth Rocks or the 

 Dominiques. The modern White Leghorn, though differing consider- 

 ably from the older type, is usually stated to be a breed which has 

 been mixed with others only to a slight extent; and it is therefore 

 commonly regarded as ''one of our purest breeds." As will be 

 demonstrated later this conception is rather doubtful. So much 

 regarding race-purity is not usually said of the Black Hamburgs, 



