A NEW SEX-LINKED CHARACTER IN DROSOPHILA. 



227 



to their vermilion barred brothers, from the above experiment, 

 vermilion barred stock was obtained which has since bred true. 

 The original male was mated to his daughters (Fi Table VII.) 

 and gave the expected proportions (Table IX.) : 



TABLE IX. 



Gametes of Fi red barred 9 , Xv br'X v Br'~X V Br'X V br' . 

 Gametes of Pi red barred <?, XV Br' 



Females. Males. 



Red Barred 9. Red Barred cf. Vermilion Normal o 1 . Vermilion Barred cf- Red Normal Q\ 

 124 37 48 18 18 



THE LINKAGE OF THE FACTOR FOR BARRED EYE. 



Since the character barred is sex-linked it follows the sex 

 chromosomes. It remains to determine its linkage with other 

 sex-linked factors. Red barred males bred to white normal 

 females gave in the F 2 generation (see Table IV.) the following 

 results: 



Total . 



80 1 



933 



715 



The non-cross over classes are red barred and white nor- 

 mal. The cross over classes are white barred and red normal 

 (Diag. la). These two categories gives 42.8 per cent, crossing 

 over. 



In order to determine the linkage of barred to another sex- 

 linked factor, viz. vermilion; red barred males were bred to 

 vermilion normal females. The F^ generation (see Table VII.) 

 gave the following results: 



The percentage of crossing over in the above case is 25.3 per 



cent. Diag. ib. 



