NEW DATA. 



39 



was mated to (red red) sable males and gave 202 wild-type^ females 

 and 184 eosin vermilion males. Two Fi pairs gave the results shown 

 in table 12 (the four classes of females not being separated). 



Table 12. — P\ eosin vermilion 9 9 X sable cf cf . Fi wild-type 9 X Fi 



eosin vermilion cf cT. 



If we combine the data for males given in table 12 with those of 

 table II, we get the following cross-over values. Eosin vermilion, 32; 

 vermilion sable, 12; eosin sable, 41. 



'In addition to these expected Fi wild-type females there occurred 13 females of an eye-color 

 like that of the mutant pink. So far as was seen none of the Fi males differed in eye-color from 

 the expected eosin vermilion. Since the eosin vermilion and sable stocks were unrelated and 

 neither was known to contain a "pink" as an impurity, these "pinks" must be due to mutation 

 of an unusual kind. That these " pinks" were really products of the cross is proven by the result 

 of crossing one of them to one of her eosin vermilion brothers, for she showed herself to be heterozy- 

 gous for eosin, vermilion, and sable. 



eosin vermilion cf. 



In addition to the combinations of eosin and vermilion, sable also appeared in its proper dis- 

 tribution, though no counts were made. The four smaller classes are cross-overs between eosin 

 and vermilion. Since no " pinks" appeared the color is recessive, and the brother was not hetero- 

 zygous for it. 



Two other "pink" females mated to wild males gave similar results in their sons. 



These Fi flies should all be heterozygous for "pink." A pair of wild-type flies which were 

 mated gave a 3 : i ratio — wild type 51 to "pink" 18. From the "pinks" which appeared in this 

 cross a stock was made which was lost through sterility. Females tested to males of true pink 

 were also sterile, so that no solution can be given of the case. 



