THE AMERICAN NATURALIST [Vol. XL V 



5 in an egg incubator at 39° C, kept there for varying 

 periods, then removed into a warm room (diffuse light, 

 21° C.) until hatching. These were divided into lots as 

 follows: 



80A, 4 pupa?, incubator 1 day, all hatched in March. 



80B, 3 pupa',, incubator 2 .lays, all hatched in February and March. 



80C, 3 puptp. incubator 3 days. 2 hatched in March. 



80D, 3 puptr. incubator 4 days, all hatched in March. 



80E, 3 pupse, incubator 6 days, 2 hatched in February. 



80F, 3 pupffi, incubator 7 days, all hatched in February and March. 



80G, 3 pupa;, incubator 2S days, all hatched in March. 



Twelve pupa?, lot no. 84, were placed in an egg incu- 

 bator from January 22 to February 18, then removed 

 to diffuse light in a warm room (21° C.) for hatching; 

 the temperature in the incubator was 39° C. until Jan- 

 uary 28, after that 39.5° C. Nine of these hatched in 

 March and April. 



D. Experiment* irith Loire r Temperature 

 Seven pupae, no. 41, were placed in a tight covered and 

 dry glass jar in an ordinary ice refrigerator from De- 

 cember 7 to March 29, afterwards removed to a warm 

 room; three hatched May 17, the others were destroyed 

 by an accident. 



Thirteen pupa?, no. 67, were treated similarly; two 

 hatched on May 17, the others were killed accidentally. 



E. Results of the Experiments 

 The pupa? were exposed to unusual external condi- 

 tions: removed from the cocoon, exposed to direct sun- 

 light with and without a heat filter, to diffuse light, to 

 various temperatures ranging from 0° C. to 39° C, with 

 the stigmata covered with balsam, in horizontal and 

 vertical positions. Yet nearly as great a proportion 

 hatched as in the case of the controls. Higher tempera- 

 tures hastened the rate of development. Further, the 

 pupa? so abnormally treated did not differ in coloration 

 from the controls or to no extent that could be measured ; 



