On the Seasonal Dimorphism of Butterflies. 4 1 



which the temperature fluctuated between 12 

 and 24 R. ; but, in spite of this high temperature, 

 and what is certainly of more special importance 

 notwithstanding the want of cooling at night, only 

 one butterfly emerged the same summer, and 

 that a male, which, from certain minute charac- 

 teristic markings, could be safely identified as var. 

 Bryonice. The other pupae hibernated in the 

 heated room, and produced, from the end of 

 January to the beginning of June, 28 butterflies, 

 all of which were exquisite Bryonice. 



Experiment thus confirmed the view that 

 Bryonice is the parent-form of Napi, and the 

 description hitherto given by systematists ought 

 therefore properly to be reversed. Pieris Bryonice 

 should be elevated to the rank of a species, and 

 the ordinary winter and summer forms .should be 

 designated as vars. Napi and Napecz. Still [ 

 should not like to take it upon myself to increase 

 the endless confusion in the synonomy of butter- 

 flies. In a certain sense, it is also quite correct to 

 describe the form Bryonice as a climatic variety, for 

 it is, in fact, established, if not produced, by climate, 

 by which agency it is likewise preserved ; only it 

 is not a secondary, but the primary, climatic variety 

 of Napi. In this sense most species might pro- 

 bably be described as climatic varieties, inasmuch 

 as under the influence of another climate they 

 would gradually acquire new characters, whilst, 

 under the influence of the climate now prevailing 



