440 T. H. MOKGAN AND C. B. BRIDGES 



Red heterozygous for eosin, vermilion and pink 



When a vermilion pink female is mated to an eosin male, all 

 the red-eyed daughters are heterozygous for eosin, vermilion and 

 pink. The vermilion eyed sons are heterozygous for the non-sex- 

 linked factor, pink. The vermilion pink permutation has been 

 described under the name 'orange' and figured in ''Further experi- 

 ments, etc." cited. The color is a deep true orange, darker 

 and brighter than the color of the eosin male. There is a light 

 cloudy yellow fleck. The color of the male is identical with 

 that of the female. 



p vermilion pink 9 XWvp — XWvp 

 ^ eosin cf X w^ V P — P 



These Fi females although heterozygous for these three factors 

 are indistiguishable from the wild red-eyed females. The het- 

 erozygous vermilion male will be considered later, with the 

 other vermilions. 



A suspicion having arisen as to whether a difference in color 

 might exist when the factors came in from the egg rather than 

 from the sperm, red females heterozygous for these same three 

 factors, namely, eosin, vermilion and pink, were produced by 

 mating, to a wild female, males of the eosin, vermilion, pink stock. 

 The method by which this stock was obtained has been given 

 and the eye color figures, in "Further experiments with muta- 

 tions in eye color of Drosophila," cited before. The colored 

 figure (5) shows at about the center of the left eye, the true color 

 of the eosin vermilion pink female. The race is bicolored, the 

 corresponding male being a trifle lighter than the female, al- 

 though this bicolorism is not strong enough so that a separation 

 made on color alone is found to be a complete sex separation also. 



