456 



BRADLEY 



7 2 



EXPOSURE TIME, days 



Fig. 1 Means ± standard errors (J) of tolerances to high tempera- 

 tures of E. affinis exposed to 10, 18, and 24°C. 



EXPOSURE TIME, days 



Fig. 2 Means ± standard errors (J) of tolerances to low temperatures 

 of E. affinis exposed to 4, 10, and 15°C. Females exposed at 4°C for 

 2.5 days all had the maximum score (50). 



which the temperature was raised 1°C every day. Five of the flasks 

 were removed when the temperature reached 27°C and kept at that 

 temperature. The other five remained in the water bath until the 

 temperature reached 29°C. The number of ovigerous females among 

 the progeny in each flask was counted over a 3-day period. 



In another experiment on reproductive success, females and 

 males collected at 0°C were exposed to 27, 28, and 29°C and 



