No. 559] BARRED PLUMAGE PATTERN 423 



birds is to be explained. Since it would be impossible 

 for the Black Hamburg females to carry the barring fac- 

 tor, unless they also possessed an inhibition for barring, 

 the obvious conclusion is that this pattern came from 

 the White Leghorn. We may tentatively assume then 

 that the W. L. £ is homozygous for barring, and attempt 

 to ascertain to what extent the experimental results 

 agree with the expected results in such a case. 



First, it may be said that the W. L. breed in all prob- 

 ability carries a factor for black pigmentation (N). and 

 also a factor which inhibits the manifestation of black 

 in the plumage (/). Furthermore we may assume that 

 it possesses a color factor C, and that the male is homo- 

 zygous for the absence of the female sex factor, F, for 

 which the females are heterozygous. In addition to this 

 we may assume that in gametogenesis the barring fac- 

 tor, B, is repelled by F. There is no reason for assum- 

 ing that the W. L. £ is other than homozygous for /. 

 We may then write the zygotic formulas of the W. 

 L. g as: 



