NEW DATA. 



29 



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

 and selection. 



Fig. B. — Bifid wing, c and d show the typical condition of bifid wings. All the longitudinal veins 

 are fused into a heavy stalk at the base of the wing, a shows the typical position in which 

 the bifid wings are held. The small size of the wings in a and 6 is due to the action of a 

 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 determining the chromosome locus of bifid 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, IQ13. 



