290 THE ENTOMOLOGIST. 



experiments. Will the new forms which have been obtained by 

 these experiments be capable of reproduction ? 



Qualitatively, the best material for this purpose would be the 

 above-mentioned phylogenetic progressive forms obtained by these 

 warmth and cold experiments. Their coloration has undoubtedly 

 been directly influenced by the experiment, and the forms in 

 question, having never been noticed in a state of nature, they 

 are individuals with acquired new characters. 



The use of these forms has, however, as far as the present 

 experiments have gone, been prevented, as the individuals 

 obtained have never shown sufficient energy ; they had certainly 

 suffered by the experiment. 



Especially the most extreme forms, which would have been most 

 fitted for these heredity experiments, had generally badly deve- 

 loped wings ; blood oozed from several places, so that they were 

 absolutely useless for the purpose of continuous flight. Besides 

 the wings, the claws on the feet of the extreme forms were, as a 

 rule, badly developed, and absolutely useless for holding on with. 

 One was therefore reduced, on the one hand, to the coloration 

 anomalies and aberrations, which were only an indirect result of 

 the influences applied, but whose anomalies, on the other, never 

 occur without such experimental influences amongst countless 

 thousands of individuals, and which constitute, like the first, 

 new forms, only with greater individual differences, and partly 

 in quite different directions. 



The experiments showed that only the frost experiments 

 produced a great number of these forms with full energy, so 

 that only material obtained by this means was used for the 

 experiment. Further, it seemed advisable to first make these 

 experiments with the Vanessa species feeding on nettle, on 

 account of the comparative ease of cultivating large quantities 

 of this plant in large pots. V. c-album, V. urticce, V. cardui, and 

 V. atalanta were all equally serviceable ; they all live, as a rule 

 or occasionally, on nettle, and, moreover, these species were 

 especially suitable, as in our latitude they constantly occur in 

 two generations. 



Finally, I was unfortunately only able to get a sufficient 

 quantity of imagines for this experiment of V. urticce, in all 

 from not less than 8231 pupae. 



Sufficient room for the experiment was kindly placed at my 

 disposal by Herr Dr. G. Stebler, in a portion of a growing-house 

 for the Seed Control Station. Good ventilation was assured by 

 replacing some of the panes of glass by wire screens. 



Four immense tubs and other articles containing full-grown 

 nettles, which had been cultivated the previous year, as well as 

 a lot of pots containing flowering pinks, completed the furnishing 

 pf the small room, to which the sun had good access. Arrange- 



