LETHAL FACTORS IN DROSOPHILA 



543 



TABLE 8 (b) 



Harris Stock 



To determine the approximate location of the lethal upon the 

 chromosome virgin females of the fifth generation (table 11) 

 were mated, some to sable males, and some to bar eyed males. 



The counts of the second generation of crosses with sable and 

 with bar eyed males are shown in table 12. The 1 : 1 ratios are 

 omitted. 



The data in this table show that the distance of this lethal 

 from bar is 8.3. 



If the locus of the factor for sable is 43 and that for bar is 

 57, the data of table 12 show that the locus of the new lethal is 

 43 + 23.5 or 66.5, since the distance of lethal from the factor 

 for bar is only 8.3. The locus of the lethal must be 'to the right' 

 of both factors since 43 + 23.5 or 66.5 is approximately equal 



