153 



NEW EXPERIMENTS ON THE SEASONAL DIMORPHISM 

 OF LEPIDOPTERA. 



By Dr. August Weismann. 



(Translated from the German by W. E. Nicholson, F.E.S.) 



(Continued from p. 113.) 



IV. Experiments with Pararge egeria and meione. 



The satyrid, Pararge egeria, L., which in our woods has two 

 quite similarly coloured broods, occurs, as is well known in the 

 South of Europe, in a golden-brown form instead of the whitish- 

 grey form, which has been described as var. meione. Both forms 

 are figured in my old paper of the year 1875, on pi. 2, figs. 23 

 and 24 ; and it is, indeed, also stated there that the extreme 

 meione, as it occurs in Corsica, Sardinia, and Sicily, is connected 

 with the German egeria by an intermediate form, whose habitat 

 is on the Ligurian coast, and which, indeed, is considerably 

 yellower and darker brown in colour than egeria, but yet has not 

 the complete brilliancy of the Sardinian variety. 



It was a question with me to know, whether both these forms 

 are wholly temperature forms in the sense that one owes its 

 appearance to the direct influence of the southern heat, ivhich 

 at present exists, the other to the influence of the northern 

 tempered warmth, which at present exists. If this was the case, 

 then a brood of meione reared under the cooler German climate 

 must produce the German form of the species P. egeria ; and, on 

 the other hand, a brood of German egeria reared in the south 

 must produce the golden-brown butterfly of the var. meioiie. 

 But if the influence of the climate is such, that it alters the 

 germ, then the experiment must give another result ; the golden- 

 brown variety of the south must still always exhibit in its pro- 

 geny the characters of meione entirely or in part, although they 

 were reared under a northern sky ; and, on the other hand, the 

 progeny of the German egeria can no more reach the golden 

 colour of the meione-ioxm. by high temperature during the 

 pupal period. 



I have conducted both experiments, and the result was de- 

 cisive, notwithstanding the many deficiencies, which always 

 attach to such experiments. I regard it, for instance, as one of 

 such, that I was not able to conduct the first-named experiment 

 with the extreme meione-iorm., but with the meione of the Riviera, 

 which is less strikingly different from the German egeria. 



First experiment ivith egeria. — 24 eggs were laid by a female 

 meione captured at Genoa, which hatched on April 21st, 1884, at 

 Freiburg, at a room temperature of 17° C. They fed on various 

 grasses {Triticum repens, species of Poa), and were placed on a 

 Poa grown in flower-pot covered with a bell-glass, and kept in 



