EYE COLOR IN DROSOPHILA MELANOGASTER 353 



The result obtained in this F2 was entirely unexpected; for 

 cherry, which is allelomorphic to eosin and so closely similar as 

 to be distinguishable only in the males, gave a totally dissimilar 

 reaction with whiting, the double recessive, cherry whiting, being 

 indistinguishable from cherry both in males and females (table 

 10). This result is very clearly shown by the males of this Fo 

 which closely approach the ratio 4:3:1. A corresponding con- 

 dition is revealed in the females, for not a single colorless female 

 occurred, and though the females were of four main genetic 

 types they were objectivelj^ of but a single class. The whole 

 ratio in this Fo was then 12:3:1 exactly as would be the case 

 in the F2 from an outcross of (eosin) whiting male by wild female; 

 that is, cherry is similar to the wild-type allelomorph red in its 

 interaction with the whiting gene. It was observed in the F2 

 from (eosin) whiting by white that the eosin-white whiting female 

 is colorless; in this experiment we observe that the eosin-cherry 

 whiting female is not thus diluted. This comparison shows that 

 there is here a total dissimilarity in the reaction of the allelo- 

 morphs white and cherry. The fact that cherry whiting is in- 

 distinguishable from cherry proves a like dissimilarity of the 

 allelomorphs eosin and cherry. The entire group of experiments 

 reveal how curiously specific whiting is in its power of dilution, 

 giving with eosin and with white the extreme amount of dilution, 

 and with red and with cherry the other extreme of dilution — no 

 dilution whatever. 



One further test of the lack of reaction of whiting with cherry 

 was made without the presence of eosin in the cross. The Fi 

 cherry males from the cross of cherry female by (eosin) whiting sp. 

 male were heterozygous for the whiting gene. One of these males 

 was outcrossed to pure cherry females and from the Fi cherry 

 males and females two mass cultm'es were made (table 11). 

 One-sixteenth of the flies hatching from these new cultures should 

 be whiting as well as cherry, while the eosin has been entirely 

 eliminated. None of the 678 cherry flies from these cultures 

 was diluted, a result which confirms the conclusion that the 

 double recessive cherry whiting is not visibly different from 

 cherry. 



