COOL AIK EXFERI.MHNTS WITH JUNOMA 

 COEMA 



WILHELM SCIIRADER 



In my first article on tcmppraturp experiments, pul)lishc<l in Vdlinne 1\'. 

 Xo. 1 of this Journal, I described only Itreedinj,' exinrimeiits at tlie warmth of 

 90 decrees, and as I found that eool air has a very difTi-rent inlluenee on the 

 formation of the markinfjs and eolor of this hutterlly, I determini'd to >rive 

 these experiments a very eareful observation, and to repeat them several times, 

 to he sure that it is the eool temperature only, whieh prodiiecs these chanpes. 



In the fall of 1010 I took eitrht.v-five younp caterpillars from my thir- 

 teenth generation whieh were bred in DO deprees damp air, and in darkness, 

 and raised these younfi taterpillars in a shad.v place, in an open shed, where 

 tlie lowest averaffc temperature at nifrht, for the first half of October, fell to 

 t!0 deijrees and th(> hifrhcst averape in the daytime from 11 to 9 o'clock was 

 about 75 dgrees. I obtained the first chrysjdidcs on October ITth, anrl the first 

 butterflies, bred in the same temperature on October 26th. In this part of the 

 thirteenth generation. I got a high percentage with double ocelli on the fore 

 wing: however, what was still more remarkable, all had both ocelli of the hind 

 wing greatly enlarged: this was .so much the more striking as in the previous 

 generations lired in a warm temperature, the ocelli of the hind wing beeame 

 slowly reduced in size, from one generation to an/ither. This enlargement of 

 the spots was not the only result, as many developed new small oeelK, which 

 were between the large and small ones and just above the latter. This is 

 shown in Fig. 253, 1. The remainder of the chrysalides from the caterpillars 

 raised in a cool temperature I bred in 90 degrees warm, damp air, and in 

 darkness; here also there was the same result, but there were not so many with 

 the new small ocelli, and the ground eolor was darker (Fig. 253, 2). In all 

 bred in a cool temperature the ground color is sonu-what lighter near the bor- 

 der, and shows generally a yellow band on the outerside of the ocelli of the 

 hind wing, the same as in our local form: the lighter ground color occurs in 

 all bred in cool temperature, in darkness as well as in the light. The under- 

 side also ehaniri's in color. In all Jnn/mia bred in warm, dry air. in darkness 

 or in light, the under side of the hind win-r is lariroly of a uniform gray, only 

 the middle field is somewhat darker: this gray color occurred alwa.vs in the 

 twelve successive generations bred in a warm temperature: however, the thir- 

 teenth -rcneration bred for the first time in a cool temperature shows the under 

 side of the hind wing, and the tip of the fore wing a brownisb-reil color, with 

 the middle field .somewhat violet: this color deepens with the fall in tempera- 

 ture, and the length of time the chr.vsalides are exposed to it. This change in 

 shade will easily account for the variously colored undersides of .7. roenia in 

 our Ea.stern and Middle Western States, where it is cold enouch to eive the 

 chrysalides a long rest. 



