380 



rate or acclimation; (b) stimulation due to change of temperature; 

 (c) development of enzymes at the higher temperature. 



The failure to pupate in the variable-temperature experiments was 

 36%, and the pupal mortality was 28%. This reduced loss is due at least 

 in part to the more favorable effect of variable temperatures as compared 

 with constant ones. In the early approximately constant-temperature 

 experiments, there was more variation and smaller loss than in the later 

 experiments in which the variation was reduced by improving the 

 equipment. 



In Townsend's experiments with the 1923-24 generation, the stocks 

 were stored at 50° F. (10° C.) ; 32° F. (0° C.) ; and 71.6° F. (22° C). 

 The percentage of pupation was highest in stocks stored at 50° F., next 

 at 32° F., and lowest at 71.6° F. This indicates that changes go on at 

 32° F., and that temperatures as low as freezing must be taken into 

 account in considering failure to pupate or the breaking of dormancy. 



Table XV. Showing data used in calculation of alpha values iy formula 

 y (X — a) = K. 



