NEW DATA. 



59 



being long, slender, and tapered (see Plate I, fig. I ), are greatly shortened 

 and crinkled as though scorched. The ends are forked or branched, 

 bent sharply, or merely thickened. The bristles 

 which are most disorted are those upon the 

 scutellum, where they are sometimes curled 

 together into balls. 



LINKAGE OF VERMILION AND FORKED. 



Since forked arose in vermilion stock, the 

 double recessive for these two sex-linked fac- 

 tors could be used in testing the linkage rela- 

 tions of the mutation. Vermilion forked males 

 were crossed to wild females and gave wild- 

 type males and females, which inbred gave 

 in F 2 the results shown in table 39. Forked 

 reappeared only in the males in the following 

 proportion: not-forked 9 , 742; not-forked rf, FIG. E.-Forked bristles. 

 346; forked cf, 301. The result shows that the character is a sex- 

 linked recessive. 



TABLE 39. 



PI wild 9 9 X vermilion-forked cf cf. F\ wild-type 9 9 

 X FI wild-type 



In table 39 vermilion forked and wild-type are non-cross-overs, and 

 vermilion and forked are cross-overs, giving a cross-over value of 25 

 units. The locus, therefore, is 25 units to the right or to the left of 

 vermilion, that is, either about 58 or 8 units from the yellow locus. 



LINKAGE OF CHERRY AND FORKED. 



Forked males were crossed to cherry females (cherry has the same 

 locus as white, which is about I unit from yellow) and gave wild-type 

 females and cherry males. These gave in 2 the results shown in 

 table 40. The non-cross-overs (cherry and forked) plus the cross-overs 

 (cherry forked and wild type) divided into the cross-overs give a cross- 

 over value of 46 units, which shows that the locus lies to the right of 

 vermilion, because if it had been to the left, the value would have been 

 8 (i. e., 33 25) instead of 33 + 25 = 58. The difference between 58 



