Constitution of the White Leghorn Breed. 189 



Instance 4- — If we assume that the W. L. Bantam was heter- 

 ozygous for / and B, and that B is, in this case, a sex-hmited char- 

 acter, we should expect to find, among 24 individuals, 12 white and 

 12 dark; of the latter, 6 would be black 99 and 6 barred d^d^. 

 Actually Davenport obtained 12 whites, and 12 darks. Of the darks, 

 some (actual numbers not given) were barred and these were all d^ cf • 

 This explanation places Davenport's results in full accord with the 

 present hypothesis. 



Instance 5. — The results of this mating are consistent with the 

 explanation furnished in this paper, and suggested in Davenport's 

 report {op. cit., p. 82). The only possible difference is one of inter- 

 pretation, in that we may regard the W. L. Bantam as heterozygous 

 for /, instead of "heterozygous in white" as indicated by Davenport. 



Instance 6. — In the case of the 99 A and C the results are as 

 expected. Both birds were apparently homozygous for /. As 

 Davenport states, ''B's germ cells were probably mixed;" it was 

 doubtless heterozygous for /. 



Instance 7. — From the first cross mentioned by Hurst {op. cit., p. 

 133) we should expect nothing but white birds. The fact that 6 

 blacks and 5 "cuckoos" were observed in Fi demonstrates, as sus- 

 pected by Hurst, the "mixed" nature of some of the stock. If, as 

 was the case in Davenport's Instance 4, these impure W. L. 99 

 were heterozygous for both I and B, then we would expect exactly 

 the "curious" results obtained by Hurst. The heterozygous barring 

 of the "mixed" 9 or 99 would be transmitted only to the c^ cf 

 while it is most improbable that the 9 9 could derive barring from 

 the Houdan d^ [C2h2f'ii2[- 



Instance 8. — In Hurst's Experiment 2 {op. cit., p. 134) one would 

 expect all the progeny to be white, or white flecked with black. The 

 fact that black birds resulted from this cross indicates that some of 

 the W. L. 9 9 were not pure for /. The expected results are as in 

 Instance 7, and the fact that Hurst reports no barred cf cf is doubt- 

 less due to the circumstance that the 8 blacks did not live long 

 enough to develop barring. The sex-ratios are not reported. 



