132 ACQUIRED CHARACTERS SEC. 



acts upon them during the change into the pupa, or shortly 

 afterwards. In many a rise of temperature produces a lighter, 

 more brilliant ground-colour, a fall a darker or less brilliant ; 

 for example, in Vanessa lo, Utricse, etc. In Euprepia Caja 

 the red-yellow ground colour of the posterior wings is changed 

 by a rise of temperature into vermilion -red ; by a fall, into 

 ochre-yellow. 



Dorfmeister considered the Vanessa Prorsa, on account ot 

 the slighter definition of its marking, to be the lower form. 

 The marking of Levana is much more complex, and much 

 more finely delineated. But as the simple Prorsa is in fact 

 the higher form, it affords a perfect example of the proposi- 

 tion sustained by me in opposition to Nageli, that simplifi- 

 cation of characters can appear in new forms. 



The chief result of Dorfmeister's experiments is just this, 

 that he has obtained Prorsa, with its simple colours and 

 marking, by means of warmth from Prorsa, and in fact from 

 the summer generation of Prorsa which takes flight in August. 

 Thus in his hands the experiment, which in Weismann's with 

 few exceptions failed, repeatedly and abundantly succeeded. 

 On the other hand, he was unable to rear the cold form from 

 the cold form. 



Dorfmeister draws no particular inferences from his results. 

 He refers finally to the necessity of completing his experi- 

 ments, and emphasises his inability to decide whether the 

 modifications obtained be the direct consequences of the rise 

 of temperature, or only indirect, depending on the shortening 

 of the period of development caused by the increased tem- 

 perature. 



But it seems to me to follow decisively from the cases 

 recorded by him that the greater the warmth he applied, 

 and consequently the quicker the development, the darker 

 the colour and the simpler the marking of the Prorsa forms 

 he obtained, and therefore the farther removed they were from 



