A NEW EYE COLOR MUTATION IN DROSOPHILA 

 AND ITS MODE OF INHERITANCE. 



SHELLEY R. SAFIR. 



A cross between a long-winged, vermilion-eyed female and a 

 miniature-winged, red-eyed male yielded in the first generation 

 red-eyed females and vermilion-eyed males, both long-winged. 

 There appeared, however, in addition 15 long-winged males 

 with a new eye color. This color is of the same general tone as 

 the vermilion pink eye but is paler and somewhat creamier. A 

 lighter area may also be seen encircling the darker area of the 

 center. 



The origin of this new eye color was accounted for as follows: 

 Since vermilion is sex-linked, all the sons must be vermilion 

 whatever else they may be. Only males of the new eye color 

 appeared, wherefore it was inferred that the something else added 

 was also sex-linked. There were too many of them (15) to be 

 explained each as a separate mutation, and it seems clear 

 that the mutation itself occurred back in the stock from which 

 the mothers were taken. If one or more of these Pi vermilion 

 females were heterozygous for the new sex-linked factor we should 

 expect in F! several of the double recessive males of the composi- 

 tion cherry vermilion. (It was decided to call the new eye color 

 cherry vermilion.) 



If then this eye color represents a double recessive cherry 

 vermilion, when mated to red eye (the normal eye color) there 

 should result in FI only red-eyed offspring. Then in F 2 , if both 

 of these factors are sex-linked, there should appear four classes 

 of males, viz., the double recessive cherry vermilion, and cherry 

 and vermilion as the result of splitting cherry vermilion into its 

 components, and also red eye color which is the double dominant. 

 All the females should be red. That these results were actually 

 realized can be seen below. 



f red 9 ............ 345 



( rl ft \ I 



red 9 X cherry verm. <? = Ji JS / 1 cherry <? ......... 41 



758 ' | verm, tf .......... 54 



[ cherry verm. cT .... 120 



45 



