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SYNOPSIS OF EXPERIMENTS IN HYBRIDIZATION AND 

 TEMPERATURE MADE WITH LEPIDOPTERA UP TO 

 THE END OF 1898.- 



By Prof. Dr. Max Standfuss. 



Plate II. (Eutom. Plate VI.). 



(Continued from p. 167.) 



5. On rare occasions aberrations were produced by these 

 warmth and cold experiments, i.e. forms arose, which, although 

 not confined to any particular season or locality, are found as 

 great rarities in a state of nature sporadically all over the district 

 inhabited by the species in question, either in similar forms or 

 near approaches thereto ; forms were also obtained by these ex- 

 periments which should no doubt be included in this category, 

 but which have not yet been discovered in a state of nature. We 

 shall return to the nature of these forms later. 



For example, by means of cold an eyeless form of Vanessa io 

 was obtained ; also characteristic aberrative forms of V. urticee 

 and V. polychloros ; and by warmth, V. antiopa occasionally 

 developed a very much broadened yellow border, V. cardui and 

 V. polychloros also giving rise to aberrations. 



These aberrations were more generally obtained when the 

 effect of the warmth and cold experiments were especially 

 extreme ; so that, on account of these observations, I came to 

 the conclusion, as long ago as 1894, in my pamphlet, " The 

 Causes of Variation and Aberration in the Imaginal Stage of 

 Butterflies " (Ent. Zeitschr. Guben, 1^^94, Sept. 15th, pp. 102, 

 103) : — " Therefore it is highly probable that a large number of 

 the aberrations found in a state of nature, the reasons for whose 

 occurrence has hitherto been unknown, have been caused by 

 abnormal temperature conditions, which afl'ected the pupal 

 stage"; and that it would appear to be necessary to complete 

 the former experiments by introducing temperatures of over 

 + 40° C. and under 0° C In fact, the results of these further 

 experiments were correctly foretold by me in the year 1895 in the 

 large Handbook, pp. 291 and 292, before these experiments were 

 in any way commenced. The results obtained confirm these 

 predictions in the highest degree. 



We now come to the second series of temperature experi- 

 ments — heat and frost experiments. 



The temperatures used, + 40° to + 45° C, on the one hand, 

 and 0° to —18° — occasionally -20°C. — on the other, were, as 



''■' Translation continued by E. M. Dadd. 



2 B 2 



