SEASONAL DIMORPHISM OF LEPIDOPTERA. 165 



room. They grew up afterwards therefore at the room tempera- 

 ture (18-19° C.)> and developed much more slowly than the 

 others. On June 21 st, when six of the latter had already 

 pupated, these were only half-grow^n, and they first pupated on 

 July 2nd. There were therefore reared : — 



A. In the incubator, at about 25° C, 9 pupae. 



B. In the room, at about 18° C, 2 pupae. 



The former pupated after 20-27 days, the latter after 34 days. 

 The butterflies emerged : 



From A, in the incubator, at 27° C. : — 



On June 27th, 1 



28th, 4 



29th, 1 



On July 2nd, 1 female. 



4th, 1 



7th, 1 



Together 9 



From B, at the room temperature : — 



On July 12th, 1 

 15th, 1 



Consequently the development from egg to butterfly had lasted 

 44-47 days at the room temperature (18° C), and 29-39 days at 

 the higher temperature 



The butterflies of Lots A and B are exactly alike ; neither 

 could be distinguished in colouring and marking from such as 

 were caught in the open. 



Result of the experiments tvith egeria. — The southern form 

 meione can, indeed, be influenced by the action of a lower tem- 

 perature (10-14° C.) in its colouring, and be rendered less 

 brightly coloured ; but still they always remain brighter in 

 colour than the northern form egeria. On the other hand, a 

 brood of the northern form is not visibly altered by the action 

 of a higher temperature (25° C). I should have liked to repeat 

 this experiment with a still greater increase of the temperature 

 up to about 35° C, but hitherto I have not accomplished it. 

 Nothing, however, in the main result would be altered by this. 



V. Experiments on the Effect of variously-coloured Light 



ON the PuPiE OF LePIDOPTERA. 



It has already been frequently stated, that the quality of the 

 light exerts a direct influence on the colours of butterflies. Now, 

 although the colour-decoration of a butterfly is ready, when it 

 breaks through to the light from the dark pupal integuments, 

 yet it seems to me worth the trouble of testing by experiment 



