EYE COLOR IN DROSOPHILA MELANOGASTER 



351 



homozygous whiting had no visible effect in the absence of eosin 

 have proved that red, the normal allelomorph of white, eosin and 

 cherry, is unaffected. 



In order to observe the interaction of white and whiting, two 

 (eosin) whiting males from M114 were out-crossed to white 

 females of pure stock. The Fi females were white-eosin 

 compounds of normal color, and the sons were white as 

 expected (table 9). F2 from the cross of eosin male by white 

 female gives in equal numbers the four classes : white-eosin 9 , 

 white 9, eosin c?', and white cf. The cross of (eosin) whiting 



TABLE 9 

 The Fi and Fo offspring from the cross of (eosin) whiting males to white females 



male by white female should give this same result with the fur- 

 ther genetic subdivision of each of the four classes into 3 not- 

 whiting to 1 homozygous for whiting. Since all white flies are 

 incapable of further dilution the white whiting double recessive 

 should be white even in the absence of effect of whiting on white. 

 But in the white-eosin compound females we shall have a chance 

 to observe the interaction of white and whiting. If white and 

 eosin react in the same fashion toward the whiting gene, then 

 the substitution of one white allelomorph for one eosin in the 

 white-eosin compound should not prevent the whiting from 

 diluting the compound to a colorless eye. But if the white 

 cannot thus be substituted, the white-eosin compound should 



the journal of experimental zoology, vol. 28, NO. 3 



