NEW DATA. 



29 



the nature of beaded, since this could be eliminated by outcrossing 

 and selection. 



c ^^-^TTTf-r- ; ■ - ' ■ ~i.;\-ii-nr rF' 



Fig B -Bifid wing, c and d show the typical condition of bifid wings. ^U the longitudinal v^^^^^^ 

 are fused into'a heavy stalk at the base of the wing, a shows the JVP'-^P-^-^-^^^^^^J^^J 

 the bifid wings are held. The small size of the wings in a and h 1. due to the action o. 

 modifier of the nature of "beaded" which has been eliminated in c, d. 



LINKAGE OF BIFID WITH YELLOW, WITH WHITE, AND WITH VERMILION. 



The stock of the normal (not-beaded) bifid was used by Dr. R. 

 Chambers, Jr., for determming the chromosome locus of bihd by means 

 of its linkage relations to vermilion, white, and yellow (Chambers 

 1913). We have attempted to bring together in table 2 the complete 

 data and to calculate the locus of bifid. 



Table 2.— Linkage data, from Chambers, /p/j. 



Gens. 



Yellow bifid . . 

 White bifid . . . 

 Bifid vermilion 



Total. 



3,175 



20,800 



2,509 



Cross- 

 overs. 



182 



1,127 



806 



Cross-over 

 values. 



S-8 



5-3 



32.1 



