FERTILITY AND STERILITY IN DROSOPHILA 



175 



some offspring with wings like those of the wild fly; at least this 

 has held true through many generations of inbreeding truncate 

 brothers and sisters. The long winged flies from truncates 

 throw in turn some truncates. 



HISTORY OF THE LOW-PRODUCING TRUNCATE AND THE HIGH- 

 PRODUCING INBRED STOCKS 



In order to bring into sharp contrast the difference that exists 

 in the productivity of these two strains I have compiled in tables 

 1 and 2 the data of these two strains through several generations 

 of inbreeding. The truncates gave on an average about 50 off- 

 spring per pair, and the inbred stock about 200 offspring per pair. 

 It has been stated that the inbred flies live longer than the trun- 

 cates, but this difference, as the tables show, will not account 

 for the marked difference in production. 



Table 2 gives the history of the wild inbred stock described in 

 Part I. This was bred parallel to the truncates in table 1 and was 

 subject to exactly the same environmental conditions. 



TABLE 2 

 History of the inbred stock 



* The low. production in this case was due to inexperience in handling, 

 the females were dead at the end of the second week. 

 t Some of the flies failed to emerge from the pupae. 



Half of 



