on the colouring of Pieris napi, ce. 67 
and 56° to 45°. A temperature of 33° seems to suspend 
the physiological changes without much, if any, other 
effect, for those which were thus iced for over 3 months 
and then exposed for from 5 to 7 days to a high tem- 
perature, closely resemble in appearance those exposed 
to a similar temperature without having been iced at all. 
FEixpLANATION oF Puate LY. 
Fies. 1 and la. C. phlewas, at 80°—90°, emerging in 6 days. 
2 and 2a. C. phleas, at 83° for 10 weeks, then at 55°, 
emerging in 5 weeks more. 
3. V. atalanta, both sides, at 90°, emerging in 6 days. 
4. V. atalanta, under side only, at about 45° to 58°, emerg- 
ing in 40 to 50 days. 
5 and 5a. V. atalanta, at 45° for 42 days, then at about 
48° to 63°, emerging in 19 days more. 
F 2 
