Contributions to Experimental Entomology 557 



longation to the tip of the anterior wing. The eye-spot markings 

 of the hind-wing remain rather constant, while the eye-spots of 

 the anterior-wing vary more or less. With the enlargement of 

 the white apical spot there is a correlated great accentuation of the 

 small eye-spot lying immediately behind it. The ring of the sec- 

 ond and larger eye-spot further back was in some cases suffused 

 with black scales. It often happens that the elements of a new 

 pattern are added; thus, for example, one cannot overlook the 

 tendency to add to the row of eye-spots already existing other 

 markings of the same kind. Moreover, black dots, which are 

 often surrounded by a feeble ring, make their appearance. The 

 lower surface of the hind-wings is, without exception, deep red- 

 dish-brown and has a scarcely recognizable pattern. This color- 

 ation is not, however, the result of higher temperatures, for it is 

 present in all of the individuals taken in late autumn in the north- 

 ern states, as I have been able to ascertain by an examination of 

 a large amount of material which Mr. Doll kindly permitted me to 

 study. Specimens from the more southerly range of the species 

 have a much lighter lower surface. 



EXPERIMENTS WITH LOWER TEMPERATURES 



For producing lower temperatures I used a mixture of pounded 

 ice and cooking salt, and the experiments with intermittent tem- 

 peratures consisted in subjecting the pupae three times daily for 

 periods of two hours to a low temperature which, in most cases, 

 was for the first day —7° C, for the second day —8° C, and for 

 the third day —9° C. In the intervals the pupse were left at +6° 

 C, and after the last exposure were taken into the room tempera- 

 ture. 



All the healthy pupae produced butterflies which in the color- 

 ation and marking are a complete contrast to those which I have 

 described in the foregoing paragraphs. In these specimens, too, 

 the ground color of the wings is dark, but this deepening of color 

 extends over all the elements of the pattern. The white cross 

 band of the anterior wings is evanescent so that it is represented 

 only by a distinct, light-colored cloud. The orange-colored band. 



