No. 508] NOTES AND LITERATURE 



247 



single chromosome. In every case, therefore, the female is homo- 

 zygote for the X-eleinont. while the male is heterozygote either 

 for X and Y, or for X and absence of X. Wilson s"hows that the 

 above relations hold in a wide range of organisms, and suggests 

 that it may be a very general relation. There are reasons how- 

 ever, for suspecting that the relation is not the same for all 

 organisms. In a previous paper 2 I pointed out a number of cases 

 which indicate that the female may be heterozygote and the male 

 homozygote for sex, though some of the phenomena cited may be 

 explained on a different basis. Miss Durham and Miss Marryatt 8 

 have recently worked out one of the cases referred to in my 

 former article, which is a case in point. In certain strains of 

 canaries, black-eyed females mated with red-eyed males give only 

 black-eyed males and red-eyed females. This may be explained, 

 as the authors point out, by assuming a correlation between eye 

 color and sex. Letting X represent the chromosome element 

 characteristic of the female and Y that of the male, assuming 

 that Y is responsible for black pigment in the eye and that in 

 some individuals Y has lost the pigment-producing power, the 

 facts are rendered intelligible by the following assumptions re- 

 garding the gametic constitution of the types : 



Black-eyed female = X Y-B, in which Y and B belong to the 

 same chromosome element. 



Red-eyed male = Y-b Y-b, where the function B is absent. 



Here the females produce two kinds of eggs, namely, X and 

 Y-B, while the males produce one kind of sperm (Y-b). This 

 gives progeny of two types, namely, X Y-b (red-eyed females) 

 and Y-B Y-b, black-eyed males. All the phenomena cited by 

 Miss Durham and Miss Marryatt are explicable by assumptions 

 similar to the above, though the occasional occurrence of black- 

 eved hens in the mating of black-eyed hens with pink-eyed cocks 

 renders it necessary to assume that in some hens the X-element 

 can also give rise to black pigment, or at least stimulate ita 

 production in some other element.* The facts cited in my pre- 

 vious paper regarding the inheritance of the bar character m the 

 plumage of poultry further indicate that the female and not the 

 male may be heterozygote for sex, as do also Doncaster's results 

 2 American Naturalist, September, 1908. 



"Eep. IV, Evol. Com., Boy. Soc. authors. 



'The gametic constitution here assumed ^ h t -t 

 They assume that B and Y are separate, but that if is 

 thus giving the same results as above. 



