Cases of mimic mutations and secondary mutations in the X-chromosome &c. 7 



The location of the singed gene. 



In order to determine the location of the singed gene, singed 

 males were crossed to eosin miniature females (w'', eye color, at 1,5: 

 m, wings, at 36,1), and the wild-type heterozygous Fi females were 

 crossed singly to eosin miniature brothers, with the result shown in 

 table 1. 



Table 1. Pi, eosin miniature o 9 X singed -fd': B.C., Fi wild-type 

 ~ 9 X eosin miniature cTcf. 



sn '*' 



The males of table 1 give a percentage of recombination of 14.8 

 for eosin singed and 15.8 for singed miniature. Tliis indicated that 

 the singed locus must be about half way between eosin and miniature. 

 However, these values would place miniature less far to the right than 

 does the calculation based upon earlier and much more extensive data, 

 so it was expected that singed is really located somewhat farther to 

 the right, probably between club (cl, wings, at 16.7) and cut (ct, wings, 

 at 20.0), and it was therefore decided to determine the location of 

 v singed with reference to the latter of these two loci. 



Eosin ruby- singed males were crossed to scute echinus cut 

 females (ruby, rb, eye color, at 7.5; scute, sc, bristles, at 0.0; echinus, 

 ec, eye; at 5.5). The wild -type Fi females were crossed singly to 

 eosin ruby- singed males (Table 2). 



If the singed locus were located to the left of cut, as expected, 

 we should get scute echinus and eosin ruby^ singed cut males as the 

 result of the crossing-over between these two loci. However, this was 

 not the case. The male classes resulting from crossing- over between 

 cut and singed w^ere scute echinus cut singed and eosin ruby-, thus 



