370 THE AMERICAN NATURALIST [Vol. XLV 



C. Experiments with Hif/h Temperatures 

 Freed eggs, from cocoons collected November 4, were 



placed in an egg incubator at 39° C. for varying periods, 

 then removed to the dark of an ordinarily warmed room 

 (21° C). Those kept in the incubator for periods of 1, 

 2, 3, 4, 5, 7 days hatched in February; those kept in the 

 incubator for eight and eleven days did not hatch. 



Ten unopened cocoons and ten egg eases placed in a 

 dry covered slide box, and ten egg cases placed in a dry 

 closed jar, all at 32° C, did not hatch. Five egg cases 

 placed in a moist chamber at 28° C. hatched December 

 15 (these had been collected November 24). Four other 

 egg cases, treated like the last but with less moisture, 

 hatched in January. 



D. Experiments with Low Temperatures 



Six egg cases were placed out-of-doors in a closed tin 

 box, protected from the rain. They hatched, as was to 

 be anticipated, at the same time as the controls. 



Fourteen egg cases were placed in a closed jar within 

 an ordinary refrigerator from November 24 until March 

 29, then removed to a warm room (21° C.) ; these also 

 hatched at the same time as the controls. 



E. Results of the Experiments 

 I tried to raise the small hatched larvae by placing 

 them upon arbor vita 3 within a moist chamber; but owing 

 to the great time consumed in transferring them to fresh 

 pieces of the food plant, I was obliged to relinquish the 

 attempt, and they all died. Consequently I did not de- 

 termine whether those hatched under the abnormal con- 

 ditions differ from control larva? of the same age. 



The eggs of this species develop into larvae under 

 direct sunlight with and without a heat filter, in diffuse 

 light, in all the colored lights employed, at a tempera- 

 ture of 39° C. provided it be not continued longer than 

 seven days, as well as at temperatures at and slightly 

 below freezing. But what seems to be a necessary con- 



