556 WiUia}}! Reijf 



pupae that had been treated experimentally with cold or heat. I 

 must call attention to the fact, however, that only experiments with 

 intermittent temperatures were undertaken, and that subjection 

 to the excessive temperatures never extended beyond three days. 

 No experiments were made with high constant temperatures, 

 while the experiments with lower temperatures gave no butter- 

 flies when I subjected them to a cold of —3° C. for seven days. 

 The hatching of the butterflies usually took place about noon 

 between 11 and 2 o'clock, and, moreover, only when the weather 

 outside was fine. Although the pupae were kept in a warm room, 

 not a single butterfly hatched when the barometer was low. 



I come now to an account of the color peculiarities of the but- 

 terflies hatching from pupae exposed to diff'erent temperatures. 



EXPERIMENTS WITH HIGH TEMPERATURES 



An incubator was used for this purpose and accurate regulation 

 of the heat was accomplished by means of a thermostat. Care 

 was taken to keep the air in the apparatus moist. 



AH the pupae which I exposed to a temperature of 45° C. for 

 more than two hours, or such as were exposed to 4.4° C. for more 

 than five hours, died. Of all the pupae which remained in the 

 apparatus five hours at 43° C, only one later produced a butter- 

 fly, but this was a complete cripple. All the pupae endured very 

 well for several hours a temperature of from 40° to 42° C. My 

 method was to expose the pupae on the first day to a temperature 

 of 40° C. for four hours, the second day to 41° C. for five hours, 

 and on the third day to 42° C. for four hours. 



All the butterflies which I obtained from these heat experiments 

 diff"er from the normal form by their sharper and more vivid color- 

 ation. The otherwise chocolate-brown ground color of the wings 

 is more blackish, so that both the white and red markings stand 

 out more strongly. In some individuals the white cross-band on 

 the anterior wings is somewhat broadened. The orange-colored 

 band between the margin and the eye-spots of the hind wing is 

 more luminous, broader and crosses not only the hind wing, but 

 also sometimes shows itself in the form of an uninterrupted pro- 



