Payne: Variations and Selection 



21 



ing the selection line to eosin miniature, and to eosin ruby 

 forked, and back crossing the females to eosin miniature 

 and to eosin ruby forked males. These characters are all 

 sex-linked and according to Morgan and Bridges ('17) are 

 located in the chromosome as follows : eosin 1.1 ; ruby about 

 6; miniature 36.1 ; forked 56.5. This is the linkage test. The 



TABLE VI 



Selection line female x eosin ruby forked male 

 Fi 



Normal 

 Bristles 



5 



Bristles 



6 



Bristles 



7 



Bristles 



_8 



Bristles 



9 



Bristles 



3 



12 



52 



52 



37 



3 



Fi female x eosin ruby forked male 



Nor- 

 mal 

 Br. 



5 Br, 



6 Br 



7 Br. 



8 Br, 



9 Br. 





Total 



Mean 



num- 





ber 



5.79 



295 



4.55 



232 



4.65 



214 



5.58 



231 



5.25 



28 



4.92 



26 



4.58 



12 



5.06 



15 



Normal, wild type 

 Eosin ruby forked. 



Eosin ruby 



Forked 



Ruby forked 



Ruby 



Eosin forked 



Eosin 



64 

 143 

 118 

 56 

 9 

 11 

 7 



62 

 58 

 63 

 63 

 8 

 8 

 3 

 4 



77 



24 

 23 

 54 

 8 

 5 

 2 

 3 



57 

 6 

 8 



38 

 1 

 2 



32 

 1 

 2 



18 



i: 2 



In Table VI the Selection line was crossed to eosin ruby forked, and 

 the Fi females back-crossed to eosin ruby forked males. The table gives 

 the results in both generations. It shows the distribution of the bristles 

 and the mean bristle number of each class which appears in F2. Here 

 the mean of eosin ruby, 4.65, approaches that of the non-cross-over, eosin 

 ruby forked, 4.55, while the mean of forked, 5.58, approaches that of 

 the normal, 5.79. 



results of the eosin miniature cross are given in Table V. 

 If crossing-over occurs between eosin and miniature in the 

 females, and if there is a factor for extra bristle number in 

 the X-chromosome nearer one of these loci than the other, 

 then one of the cross-over classes should show a higher bristle 

 number than the other. Such is the case. The mean bristle 

 number of the miniature flies is 4.888, approaching that of the 

 normal (5.222) one of the non-cross-over classes, while the 



