( c vi ) 



It is perhaps to be expected that this alteration of colour in 

 the wing should take place during the latter part of the pupal 

 stage, for it is at this period that the hflemolyinph or blood 

 from which the pigment of the scales is formed flows into 

 them.* This hamiolymph, at first yellow and then drab, can 

 by various chemicals be made to assume many colours, in- 

 cluding reds, yellows and bright carmine. We have thus the 

 raw material provided by nature out of which various colours 

 can be elaborated. 



Is it protective ? 



Is this difference in ground colouring which I have de- 

 scribed protective 1 I think there is ground for saying that it 

 may be so. It has a strong likeness to the difference between 

 the general aspect of vegetation in different seasons, between 

 a hillside parched by an August sun and the dark stems of 

 the undei'growth of wet woodland ; and the lighter coloured 

 insect should be better adapted for concealment in seasons 

 or in regions where the colour of dead vegetation is the 

 prevailing one. 



Can these temperature effects become hereditary ? 



There is weighty opinion in favour of the view that some of 

 the effect produced by abnormal temperature on the facies of 

 a butterfly of which the pupa has been exposed to it for a 

 single generation can be passed on to the progeny. Professor 

 Standfuss adduces evidence to that effect in the case of V. 

 uriiav. Dr. E. Fischer has stronger evidence, derived from 

 some experiments on Arctia caja. Professor "Weismann 

 accepts the conclusion that in these cases the aberrations 

 of the parents induced by cold descended in a considerable 

 degree to the offspiing, explaining this by the view that 

 the germ plasm is affected, some of the " determinants " being 

 strengthened, others weakened by it;t and he elsewhere 



* A. G.Mayer, " Development of Wing Scales," etc., Bnll. Mus. Comp. 

 Zoology, Harvard College, June 1896, as to the vital structure developing 

 in the papa earlier than in the wings. See Ent. Record, vol. i, p. 298. 



t "Weismann "The Evolution Theory," translated hy Mr. and Mrs. 

 Thomson, vol. ii, pp. 267 and 275, also p. 137. See also his observations 

 on my experiments on C. phlxas, Neuc Ycrsuche, etc., English translation, 

 p. 10. 



