246 



THE AMERICAN NATURALIST 



[Vol. LYI 



all sons of the Columbian females are white (Colum- 

 bian) while all the daughters are buff. 



The mating of Fi buffs inter-se produced only buff 

 •chicks, indicating that buff is recessive and breeds true. 

 The nine chicks recorded as buff and white all had buff 

 lieads or wings or both and those which lived developed 

 buff adult plumage. G-enetically they were probably ex- 

 tremely light buffs. 



As regards only the difference between white and buff, 

 ive may conclude that the Columbians contain a dominant 

 sex-linked gene for the inhibition or restriction of buff 

 from the j)lumage. The first male was evidently hetero- 

 .'zygous for this factor; the second male was homozygous 

 for it; the Columbian females contained but one dose of 

 it, and this was located in the single sex chromosome; 

 while all the buffs lacked it entirely. This is evidently 

 the same gene (I) which Sturtevant (1912) found in Co- 

 lumbian Wyandottes, although its effects were somewhat 

 obscured by other factors in his crosses with Brown Leg- 

 horn. 



The presence of this gene in some White Wyandottes 

 which I have studied strengthens the homology between 

 the gene with which Sturtevant was dealing and the gene 

 which is present in the Light Brahma s used in these ex- 

 periments. I have recently crossed two White Wyandotte 

 males with purebred Buff (Orpington) females. The 

 white males were known to be recessive white (cc), i.e., 

 they lacked the gene (C) for the development of color 

 in the plumage. The results of this cross are shown in 

 the table following. 



Down Colors 13 13 26 



3 



16 



In addition to the ty]C)es noted above three unclassified 



