No. 534] INFLUENCE OF CHANGED CONDITIONS 365 



Diffuse Sunlight. — Five pupae, lot no. 65, were placed, 

 each vertical with head up in a test-tube in a room that 

 never sank quite as low as freezing; all hatched between 

 May 15 and June 2. 



Five pupae, lot no. 66, were kept under similar condi- 

 tions, but placed with their heads down in the test-tubes ; 

 four of these hatched in May, the fifth being infected 

 by parasites. Three pupae, lot no. 69, were placed verti- 

 cally in separate tubes within a moist chamber near a 

 steam radiator in my private laboratory; two hatched 

 in February, the third died. 



B. Experiments with the Tracheal Stigmata Covered 

 Twenty pupae, lot no. 85, were placed in a warm room 

 (21° C.) in diffuse sunlight. On January 22 the stig- 

 mata, of which there are eight easily recognizable pairs 

 counting those of the head, were covered with a gum- 

 arabic solution, but this peeled off and was replaced the 

 next day by pure Canada balsam. It is, however, quite 

 doubtful how efficient the balsam was in excluding air 

 from the respiratory tubules, for it does not adhere very 

 well to the greasy surface of the cuticula. Four of these 

 pupae, lot 85A, had seven stigmata of the right side cov- 

 ered, and all hatched. Four others, lot 85B, had the first 

 pair of stigmata covered, and all hatched. Four others, 

 lot 85C, had the second and third pairs of stigmata cov- 

 ered, and all hatched. Four others, lot 85D, had the 

 sixth and seventh pairs covered, and three hatched. 

 Four others, lot 85E, had the fourth pair covered, and 

 three hatched. 



C. Experiments ivith Higher Temperatures 

 Ten pupae, lot no. 68, were placed within a closed and 

 dry glass jar in diffuse light, kept thus at 28° C. for 23 

 days, then removed from the jar and kept in diffuse light 

 in a room at 21° C. All hatched, except three that were 

 parasitized. 



Twenty-two pupae, lot no. 80, were placed on January 



