TWO NEW EYE COLORS IN DROSOPHILA MELANOGASTER. 2O5 



by mating the FI female from the cross sooty X rose, to a rose 

 sooty male fly. The FI female was used instead of the FI 

 male for the reason that there is no crossing over in the male of 

 this species. The double recessive rose sooty had been obtained 

 by mating F 2 sooty by F 2 rose flies. The percentage of cross 

 over from the back cross was 21.1. This therefore is the strength 

 of the linkage between sooty and rose. 



/Rose 647 

 JNon cross overs -{ 



I booty 634 



r 2 



fRose sooty 173 

 Cross overs i , 



I Wild-type 170 



Percentage of cross over, 21.1. 



Rose was next crossed to pink, a third chromosome character 

 of known linkage and with locus 16. The FI were intermediate 

 between the two parents, and when inbred gave only F 2 of the 

 same eye colors. This showed conclusively that pink and rose 

 are allelomorphic. 



The linkage relations of rose should of necessity be the same 

 as those of pink. According to previous work pink had been 

 placed at a distance of about 18 units from sooty, whereas the 

 present data indicate a distance of 21.1 units between these 

 factors. This small difference in the percentage of crossing over 

 may be due to one of a number of causes. 



Another allelomorph of pink, peach, had previously been 

 identified. When peach is crossed to rose, flies with intermediate 

 eyes resulted. Rose is therefore the third of a series of allelo- 

 morphs at the approximate locus of 16 on the third chromosome. 



SUMMARY. 



In a series of temperature experiments, during which cultures 

 of Drosophila melanogaster were incubated, many new variations 

 appeared. Only one, scarlet eye color, similar in appearance to 

 "vermilion" of the first chromosome group, was found to be a 

 true mutation. Scarlet is a third chromosome character whose 

 gene is on the sepia side of dichsete at a locus of 3.2 from the 

 latter. The same eye color has arisen as an independent muta- 

 tion at Columbia University in the cultures of D. E. Lancefield, 

 whose paper is also in this journal. When crossed, the two strains 

 give FI like the parents. 



