April, '10] SANDERSON: TEMPERATURE AND INSECT GROWTH 



127 



ture from this point alike resulting in retarding the growth or activity. 

 This point is the optimum (Z.). "When the upper temperature limit 

 of activity is passed, at W, heat-rigor ensues. If the heat be increased 

 to a point A, death will result in a short time. This point, A, is known 



10° 



14° 



20° 



26° C. 



Days 



;h: 



p.: 



I 



i 



Fig. 19. Relation of temperature to the incubation of eggs of Carpocapsa 

 pomonella in Arkansas, according to Jenne, 1908 (original). 



as the maximum. But a temperature above A may be -endured for a 

 short time before death, but if the insect is brought to a temperature 

 of B death is practically instantaneous due to the coagulation of cer- 

 tain proteids of the protoplasm. Although heat-rigor occurs at any 

 point above "W, the effect of it is due to the length of time of the 

 exposure. Thus a varying length of exposure, according to the amount 



