experiments on some Lepidoptcra. 137 



clear results. I should premise that in describing the 

 colours, I only mention the broad general effects. I am 

 indebted to Mr. White for the more detailed description 

 which I append. All the experiments were tried with 

 eggs from the same parent. 



The detail of the experiments will be found in the 

 Appendix (Tables VI., VIL, VIII., IX., X., XL). Some 

 were forced all through, others forced as larvae, cooled as 

 pupse. Some were kept at the ordinary temperature all 

 through ; others, having been so kept as larvae, were 

 divided into two lots, of which one was forced as pupse, 

 the other cooled or iced for 28 days or more as pupae. 

 The result may be stated as follows : — It ivas in the 

 pupal state that the effect was in the main produced. The 

 forced pupce, whatever the treatment of the larvae had 

 been, invariably p)roduced pale and comparativeli/ spotless 

 moths ; the cooled or iced pupcz, whatever the treatment 

 of the larvae had been, invariably produced dark and 

 much spotted moths* Another point, suspected last 

 year, was established — that a temperature of 63°, or 

 even higher, is low enough to produce the well-known 

 dark and spotted appearance. At the same time, the 

 colouring of the moth seems somewhat affected by the 

 temperature at which the larva has been brought up. 

 The larval period in those that were forced was about 30 

 days, the pupal about 16, total 46 days ; as against a 

 larval period of about 68 days, and a pupal of about 25 

 days, total 93 days, in the unforced. 



The moths from the forced pupae are mostly smaller 

 than the others, but this may be an accident, resulting, 

 perhaps, from the circumstance that, owing to a relaxa- 

 tion of vigilance in the beginning of June, they were 

 exposed for 3 days to a temperature of 90° — 100°, 

 which caused many deaths. 



It will be seen that there is some individual variation, 

 more particularly in the pupae exposed to the ordinary 



-'' There is little difference in general appearance between the 

 moths from the cooled pupae of forced larvae, and the moths from 

 the cooled pupae of larvae bred in the ordinary temperature ; such 

 as exists is perhaps partly owing to tbe fact tliat the latter were 

 exposed generally to a lower temperature (the Refrigerator being 

 colder at the time they emerged), and in some cases for a longer 

 time. It is probably owing to this greater exposure that they have 

 a less vigorous appearance, and include a large proportion of 

 cripples. 



