138 



STURTEVANT 



Table 22 

 Total linkage data 



Stocks as nearly uniform for modifiers 

 as possible, and also to control the 

 temperature, if any reliable data were 

 to be collected as to the relative effec- 

 tiveness on facet-number of the vari- 

 ous combinations of bar and infra- 

 bar. Accordingly, a female that was 



,'' was mated to a round-eyed ver- 

 jBB ' 



milion male from vermilion stock. 

 The descendants from this mating 

 were inbred (brother-sister pair mat- 

 ings) for seven generations. In each 

 generation a female heterozygous for 

 two of the three bar allelomorphs con- 

 cerned was mated to a male carrying 

 the third allelomorph. The line was 

 made homozygous for forked; but 

 both vermilion and fused were elimi- 

 nated. No other selection was prac- 



^ Derived from the experiments of table 

 1, so that the BB of the following discussion 

 is known to have come from the BB male of 

 that table, and to have been derived from 

 homozygous bar by forked-fused crossing 



ticed. A female of the third inbred 

 generation was mated to an infrabar 

 male, and a daughter that was infrabar 

 over round was mated to a male from 

 the fourth generation. For three more 

 generations the infrabar series was 

 crossed to the inbred line. After the 

 eighth generation the pedigrees are 

 somewhat more complex, but as close 

 inbreeding as was compatible with 

 maintaining four allelomorphic sex- 

 linked genes was continued for six 

 more generations before the facet 

 counts were begun. The other types 

 studied (bar-infrabar, reverted bar, 

 etc.) were all crossed to the inbred 

 stock just described, at least five times 

 (mostly using females to allow cross- 

 ing over and get as much of the X's 

 uniform as possible) before being used 

 in the counts. This procedure should 

 have resulted in making the various 

 stocks practically alike with respect to 

 modifying genes, and the results ob- 

 tained are sufficiently consistent to in- 

 dicate that there was no heterogeneity 



