176 



ROSCOE R. HYDE 



CROSSES BETWEEN THE LOW-PRODUCING TRUNCATE STOCK 

 AND THE HIGH-PRODUCING WTLD STOCKS 



The following experiments were carried out in order to determine 

 whether the egg or sperm was responsible for the low fertility of 

 the truncates. 



Females from the low-producing truncate stock were paired to 

 males from the high-producing inbred stock. The reciprocal 

 cross was also made. Since the number of offspring bears a more 

 or less direct relation to the length of life of the pairs, data on the 

 length of life is also given. Tables 3, 4 and 5 give the result of 

 the first experiment. 



This experiment shows that the low-producing truncates were 

 producing an abundance of fertile sperm, since each was capable 

 of fertihzing on the average 428 eggs of the female of the high- 



TABLE 3 a 



Showing crosses between the low-producing truncates and the high-producing 



inbred stock 

 Truncate 9 X inbred cf 



* ' Crescent' as recorded in table 3 are longwinged flies with a small crescent- 

 shaped piece cut out of the inner margin at the end of the wing. They are a new 

 class that arise on crossing the truncates with wild stock. 



t Sterile. 



