'288 THE ENTOMOLOGIST. 



experiments have gone, with species which hybernate in the 

 larval stage. 



One must now consider the alternative as to whether the 

 aberrations are caused by extreme high temperatures. 



In these experiments, conditions which could possibly happen 

 in nature were, as nearly as possible, adhered to, and in this 

 case the experiments * were not without result, although much 

 less material was used. 



* In 1898 the heat experiments were continued in ^reat numbers with 

 + 42° to + 44° C. ; firstly in January and February with hybernated pupse 

 of Papilio podaliriiis, L., P. machaon, L., Thais cerisyi var. deyrollei, 

 Obthr., Polyommatiis amphidamas, Esp., and Vanessa levana, L. I was 

 successful in obtaining a few aberrations sensu strictiori of all these species. 

 Thais V. deyrollei produced especially striking forms. 



Plate I. fig. 7 shows an aberration oi Pajjilio podalirius, L. (hybernated 

 pupae from Sitten, Canton of Valais) thus obtained, which shows an increase 

 in the dark markings in some place on the fore wings in a blurred manner. 

 The black markings both on the upper and under sides of the fine female 

 Thais var. deyrollei, Obthr. (PI. I. fig. 9), are also very much increased over 

 the normal form. This aberration was frequently obtained by the heat experi- 

 ments. The female of the Amasin local form of Thais cerisyi, B. (PI. II. fig. 1), 

 is not so much darkened, but still differs a good deal from the ordinary form. 

 PI. I. fig. 10, and PI. II. figs. 2 and 3, show abnormal coloured specimens of 

 Polyommatus amphidamas, Esp., from hybernated pupae from Leipzig, also 

 in increased darkening ; the under sides of these individuals show a partial 

 lengthening of certain rows of spots into rays. 



In contradiction to the above-named aberrations of Papilios and Poly- 

 ommatus am,phidavias, a Lycsenid ; the nymphalid V. levana, L. (Leipzig), 

 shows a reduction of the black brown markings ; as will be seen (PL I. fig. 11, 

 and PI. II. fig. 4), at least as far as these heat experiments with hybernated 

 pupae go, I could not obtain opposite variations, or, in fact, variations in any 

 other direction. The males of Thais var. deyrollei, Obthr., in apposition to 

 their females, showed an inclination to a reduction of the dark markings, 

 which wiU be seen by PI. I. fig. 8). 



These experiments filled up a considerable blank in the former ones. 



From May until August a continuation of the heat experiments was 

 made with summer pupae. 



V. antiopa, L., resulted in a number of ab. hygicea, Hdrch., as weU as 

 intermediate forms ; two characteristic specimens of these forms are shown 

 (PI. II. figs. 5 and 6). 



According to present experience, these aberrations were most frequently 

 attained by a temperature of + 42° to + 44° C. applied three to five conse- 

 cutive days, four times a day, each application lasting one hour; the best 

 result was seven aberrations among forty individuals. The change from 

 daily temperature to heat, as in all these heat experiments, was sudden, as 

 also the return to ordinary temperature at the conclusion of the application. 



V. cardui, L., produced two ab. elymi, Ebr., one of which is shown 

 (PI. II. fig. 7) ; V. atalanta a typical ab. Memensiewiczi, Schille (PI. II. 

 fig. 8), and an intermediate. 



Several very extreme forms of ab. ichnusoides, Sel. Long., were obtained 

 from V. urticce, L., as well as intermediates ; a specimen of the first is 

 figured (PI. II. fig. 9), and an intermediate (PI. II. fig. 10). V. io, L., pro- 

 duced a few ab. helisaria, Obthr., very highly developed from individuals of 

 the second generation from Zurich (PI. II. fig. 11). Vanessa var. prorsa, L., 

 in all the large series exposed produced, first, as the earliest emergences of 



