On the Seasonal Dimorphism of Butterflies. 1 1 



marking 1 of the former, but mixed with much of 

 the yellow of Levana. 



It should be here mentioned, that similar expe- 

 riments were made in 1864 by George Dorf- 

 meister, but unfortunately I did not get this infor- 

 mation 10 until my own were nearly completed. In 

 these well-conceived, but rather too complicated 

 experiments, the author arrives at the conclusion 

 " that temperature certainly affects the colouring, 

 and through it the marking, of the future butterfly, 

 and chiefly so during pupation." By lowering the 

 temperature of the air during a portion of the 

 pupal period, the author was enabled to produce 

 single specimens of Porima, but most of the butter- 

 flies retained the Prorsa form. Dorfmeister em- 

 ployed a temperature a little higher than I did in 

 my first experiments, viz. 10 11 R., and did 

 not leave the pupae long exposed, but after 5^ 8 

 days removed them to a higher temperature. It 

 was therefore evident that he produced transition 

 forms in a few instances only, and that he never 

 succeeded in bringing about a complete transfor- 

 mation of the summer into the winter form. 



In my subsequent experiments I always ex- 

 posed the pupae to a temperature of o 1 R. ; 

 they were placed directly in the refrigerator, and 



10 " Uber die Einwirkung verschiedener, wahrend der Ent- 

 wicklungsperioden angewendeter Warmegrade auf die Farbung 

 und Zeichnung der Schmetterlinge." A communication to the 

 Society of Natural Science of Steiermark, 1864. 



