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THE AMEBIC AN NATURALIST [Vol. XLYII 



In other words, among every 16 birds in F 2 we might 

 expect to find 12 whites, 3 barred and 1 black. The whites 

 should be equally divided between the sexes ; of the three 

 barred birds, two should be male and one female; the 

 one black should be a female. Moreover, one of the 

 barred males should be homozygous for this factor, while 

 the other male and the female should be heterozygous. 

 Other birds, including both males and females, should 

 carry the barring factor but not manifest the pattern 

 since they will also be either homozygous or heterozygous 

 for the inhibiting factor, I. 



Having thus outlined what we should expect to see re- 

 sult in F 2 , provided the original W. L. cockerel was actu- 

 ally homozygous for barring and also possessed factors 

 C, N and I, we may now attempt to ascertain to what ex- 

 tent these theoretical results agree with the experimental 

 data and furnish an interpretation for them. 



First, referring back to Table I, it is apparent that the 

 expected 3:1 ratio of a white X black cross is fairly 

 closely realized among the 117 birds included in this 

 table. Actual results were 90 white: 27 dark, while the 

 expected are 88 white : 29 dark. Whereas we should ex- 

 pect only 7 + blacks, all females, we actually have 12 

 blacks (16 including the grays), including 9 females and 

 3 of undetermined sex. In part explanation of the dis- 

 crepancy it may be said, however, that in very young 

 chicks it is impossible to distinguish the blacks from the 

 barred. In case chicks die during the first week of life, 

 all those which would later develop barring must be de- 

 scribed as black. It therefore can not be doubted that 

 several of the birds described as black were actually 



