MUTATIONS IN EYE-COLOR OF DROSOPHILA. 



339 



The Vermilion-White Cross. 



This cross has been made by Mr. A. H. Sturtevant in my laboratory, to whom 

 I am indebted for the following data. When a white male (of red-white stock) 

 was bred to vermilion female of pure stock the results were • 



Red 9 242 



Red o 2^ ^d <*" 63 



White cf by vermilion 9 « v £_ * ~ \ Vermilion 9 228 



Vermilion tf 165 

 White <? 163 



Vermilion d" 24 



The analysis is as follows 



VpOCX— VpOCX Vermilion 9 

 VPocX—Vpoc White <*■ 



F 



1 



VpOCX— VPocX Red 9 



VpOCX—Vpoc Vermilion <*■ 



VpocX— VpOCX— VPocX— VPOCX 



VpOCX —Vpoc 



VpocX VpOCX = Vermilion 9 VpocX Vpoc = White tf 



VpOCX VpOCX = Vermilion 9 VpOCX Vpoc - Vermilion <? 



VPocX VpOCX - Red 9 FPocX k>c = White «*• 



FPOCX FpOCX - Red 9 VPOCX Vpoc = Red <* 



The only point in the result that calls for comment is the small number of 

 red cf's in the F 2 generation. Without any coupling that class should be equal 

 to the vermilion male class, but the result is explicable when the coupling between 

 P and C is recognized. The white males without coupling should be equal to 

 the sum of the vermilion and red males but the white males are not quite so 

 numerous as the vermilion males alone. This result can be explained as due 

 to the lower viability of the whites, a circumstance known to exist, from other 

 experiments. 



In the analysis two classes of vermilion females should occur, one homo- 

 zygous for C and one heterozygous; the latter being less frequent, owing to 

 coupling. Nine of these 9 y s taken at random were tested and seven proved to 

 contain CC and two Cc. Nine of the white males were also tested, and seven 

 were found to contain Pp, and two to contain pp. This result is in harmony 

 with the assumption of coupling between P and C. 



The Eosin Eye. 



During the summer of 1911 I carried on a mass culture of white-eyed flies, 

 with black body-color, and miniature wings, in order to get a pure white-eyed 

 stock combined with black miniature wings. This stock had been derived 

 recently from a stock of black, miniature flies derived from pink- or red-eyed 

 ancestors. As mass cultures were used, the possibility of a cross with Red or Pink 



