Constitution of the White Leghorn Breed. 193 



individuals from the "black" column, if these had lived long enough 

 to develop their barring. It is apparent, however, that the ratio of 

 cT cf to 9 9 is in the right sense. 



Turning now to the results of similar matings presented in Table 4, 

 it is apparent that the experimental results conform more closely 

 to the expected. In this case all the chicks were over three weeks 

 old when described. The obtained ratio of whites to blacks is 

 106 : 31, while the expected is 102 : 35. The actual ratio of black 

 to barred birds was 7 : 24, while the expected was 8+ : 25+. As 

 was to be expected no black cf cf appeared while the number of 

 barred d^ 6^ was approximately twice the number of the barred 

 99 (14:6), the expected being 17+ : 8+. 



It is thus clear that when only chicks over three weeks old are 

 included in the tables the actual and the expected ratios find close 

 agreement, and appear to demonstrate the correctness of the view 

 that the cf W. L. is homozygous for the barred plumage pattern. 



Case 2a. — White Leghorn X Black Spanish, Fo. — (Tables 6, 7 

 and 8, pp. 171 and 172). The 1911 results presented in Table 6 show 

 a predominance of whites and a deficiency of both black and barred 

 birds. These matings were repeated in 1912 to ascertain whether 

 the same defective ratios were present. Table 7 makes it appear that 

 both the excess of whites and deficiency of dark are still apparent^ 

 although in the case of the progeny of 14 D, S and T* the experimental 

 results are closer to the expected. What circumstance causes the 

 defective ratios shown in the totals in Table 9, cannot at present be 

 stated. In this instance, some unsuspected factor msiy be at work. 



Case 3a. — White Leghorn X Black Minorca, Fo. — (Table 9, 

 p. 173). Although only a small number of individuals were raised 

 from this mating, the experimental results, as in the case of W. L. 

 X B. H., F2, are seen to correspond well with the expected. 



Case 4a. — White Leghorn X Black Java, F2. — (Tables 15, 16, p. 

 179, 180). There is seen in the 1912 cross-breds a slight deficiency in 



*These 9 9 were raised from the Black Spanish mothers of F^ in the season of 1911. 



