Cases of mimic mutations and secondary mutations in tlie X-chromosome &.c. 9 



demoustrating- that the sing:e(l gene is located to the right and not to 

 the left of cut. There were obtained 32 recombinations of cut and 

 singed out of 3254 males, which places singed 0.9 unit to the right of cut. 

 For the final location of singed an experiment was started in 

 which the linkage relations of singed to cut and to lozenge could be 

 obtained. Lozenge eye was at that time supposed to be the locus 

 closest to cut on the right. It has later been found that tan (t; body 

 color; at 27.5) is located very slightly nearer to cut. Scute echinus 

 cut singed males from the experiment just presented were crossed 

 to buff lozenge females fiora stock (buff, w''^ eye color, at 1.5). The Fi 

 wild -type females were crossed singly to buff lozenge males (Table 3). 



Table 3. Pi, buff lozenge oo X scute echinus cut singed cTcf; B.C., 



Fl wild-t3'pe 



sc [ec] ct sn 



irbf 



T 9 X buff lozenge cf cT. 



Out of a total of 1460 males 11 were recombinations of cut and 

 singed, and 65 of singed and lozenge. This gives a distance of 0.8 

 and 4.4 units between cut and singed and singed and lozenge respecti- 

 vely. In the classifications the echinus character was disregarded since 

 this eye alteration can not he detected in flies which are at the same 

 time lozenge. 



