200 



ROSCOE R. HYDE 



Diagram F expresses the essential relation of fertility as brought 

 out in these three experiments. I shall consider the results of the 

 last two experiments in making up the average since it is evident 

 that these numbers express more nearly the actual facts of the 

 experiment. 



TABLE 20 



Back crosses betw3an hybrids {of Woods Hole and truncate stocic) and the truncate 

 stock. The table gives the number of females that entered into each cross. The 

 numbers on the left side of each column show the number of eggs isolated, the corre- 

 sponding number on the right the number of flies that emerged. 



These bottles met with an accident and are not considered in the totals. 



