210 



Bulletin No. 155. — 1913. 



Females, heterozygous for B and F, would be formed in the exactly 

 same number and proportion as those indicated above for the cf cf" • 



From this analysis it is apparent that among every 128 individuals 

 18 would be barred and 110 white, both the barred and the white birds 

 being equally divided between the sexes as follows : 



In the following table, we may compare the actual with the ex- 

 pected results in F2 as formulated upon the present hypothesis: 



♦Provided the W. L. (^ possesses the primary color factor, C. and the W. P. R. 9 9 possess no 

 contributing pigmentation factor whatever. 



fProvided the W. L. (^ possesses the " X-factor" and the W. P. R. 9 9 the " Y-factor." 



It is apparent from the summary presented above that on the basis 

 of the single-factor hypothesis we should obtain 12 barred individuals 

 in every 64, while on the double-factor hypothesis we should obtain 

 only 9 in 64. The experimental results, comprising observations on 

 61 F2 individuals, are slightly in favor of the former view. It must 

 be borne in mind, however, that the difference between the two groups 

 of expected results is slight, and final conclusions must be deferred 



