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ROSCOE R. HYDE 



truncates produced no more offspring per fertile pair than at the 

 beginning of the experiment when half of the pairs were sterile. 

 Neither can the low productivity of the truncates be explained 

 entirely because of the shortened length of life, although this is 

 one factor in the result. 



The truncates differ in many ways from the wild stock : 



1. The flies give rise to a small number of offspring per pair. 

 Table 1 gives the number of offspring produced through several 

 generations of inbreeding. Despite all the care in breeding that 

 could be exercised no way was found to increase the output. 



2. The truncate flies do not live as long as the wild fly. The 

 length of life is in general about half that of the inbred stock which 

 was used in ' the control. The two strains were bred under 

 identical conditions (compare tables 1 and 2). 



3. Truncates, as the name implies, have the ends of the wing 

 squared instead of rounded. The wings extend only to the tip of 

 the abdomen. The flies will not breed true, for they produce 



TABLE 1 



History of truncate stock through sevente en generations of inbreeding 



