DILUTION EFFECTS IN CERTAIN EYE COLORS 463 



dilution effect (vermilion pink). Starting again with pink and 

 adding eosin we obtain an eye color (eosin pink) much lighter 

 than the last, showing that eosin is a stronger diluter than 

 vermilion. 



The white eye is obviously lighter than eosin. Its influence as 

 a diluter in heterozygosis may next be shown. VermiUon hetero- 

 zygous for white and pink is lighter than vermilion heterozygous 

 for eosin and pink. Again, vermiUon pink heterozygous for 

 white is markedly lighter than vermilion pink heterozygous for 

 eosin. 



We have shown that the white-eosin compound female (w — • 

 w^) has the same eye color as the eosin male (w). The substi- 

 tution of pp for PP in the white-eosin female and the eosin male 

 dilutes the eye color of each sex to a lower common stage. , If 

 one starts with the two equal stages of color the white-eosin com- 

 pound female and the eosin male, and adds to each the same di- 

 luter or combination of diluters, then the final stages of each are 

 equivalent in color. Thus, white-eosin compound vermilion fe- 

 male heterozygous for pink is the same in color as the eosin male 

 heterozygous for pink, but both are much lighter than the eosin- 

 white compound female or the eosin male. On the other hand, 

 if one starts with the unequal stages, eosin female and eosin 

 male and adds the same diluter to each, the two colors are pro- 

 portionally reduced so that the end results have the same rel- 

 ative differences as the eosin female and male, as seen in eosin 

 pink female and eosin pink male. 



In certain combinations it is possible to lower the eye color 

 of the female by half a step which is not possible in the male 

 because of the diploid nature of the female in sex-linked charac- 

 ters and of the haploid condition of the male. For instance, the 

 vermilion female heterozygous for white and pink is lighter than 

 the male heterozygous for pink. A better case is that of ver- 

 milion pink female heterozygous for eosin or white being lighter 

 than the vermilion pink male. Again white-eosin pink female 

 heterozygous for vermilion (X w V p/X w" v p) is lighter than the 

 eosin pink male (Xw^Vp/ p. She is also lighter than the 



THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 15, NO. 4 



