dHEMISTRY OF INSECT COLOURS. . 5t 



The partial reversions of Deiopeia HCl, and E. jacohcem, 

 HCl, have now become complete reversions to the natural red. 



The partial reversion of jacohcece H2SiF6 is still only in the 

 intermediate condition. 



And in addition the following reversions have also occurred: — 



Deiopeia bella. H2SiF6, pretty fairly red (pink). 



C. nupta. HCl, almost fleshish. 



C. hera HCl, a red (i. e., not quite the natural red ; cp. supra). 

 Here, owing to the pressure of other work, my observations 



were discontinued, and the experiments were left to themselves 

 for several months. The following observations were made on 

 November 5th : — 



Z.filipendulce. H2SO4, red. 



E.jacobcece. H2SiF6, reversion to red never completed. 



D. bella. H2SiF6, red (pink). 



C. hera. HCl, deep red ; H2SiF6 and C2H2O4, fairly red. 

 HaSOi, red not recovered ; but the wing not so much yellow as 

 transparent. 



C. nupta. HCl and C2H2O4, a tolerable red. H2SO4, reddish 

 orange. 



Finally, a last observation on Nov. 30th showed — 



C. nupta. HCl, H2SO4, C2H2O4 : all fairly red, or at least 

 deep flesh. 



C. hera. C2H2O4 and H2SiF6, also red. 



As to the remaining experiments, I should say that two (of 

 which it may be noticed that no record is given above), viz., Z. 

 Jilipenduke, HsPOi and C2H2O4, came to an early and untimely 

 end ; whilst the atalanta experiments, in which it was perfectly 

 clear that no reversion ever could take place, were abandoned after 

 a few weeks' standing. Were it not entirely superfluous and 

 unnecessary as evidence for what I had already abundantly proved, 

 there would be considerable interest and importance attaching to 

 the fact that two of the nitric-acid specimens, viz., hera and 

 nupta, which had been allowed to remain for over five months, 

 were still as yelloiv as a lemon, although not the least acid could 

 be detected in them by that most sensitive test of — the tongue.* 



I may add that, complete as the evidence for reversion now 

 seems to be, fresh data are accumulating ; for now, in experi- 

 menting on the various red species that have been sent to me, 

 I make a rule of ascertaining afterwards the reversion behaviour. 

 It is, however, — at least for the present purpose, — hardly necessary 

 to add anything to what is stated above.! 



* It is not uninteresting that in — at least some — cases where the red colour is 

 restored, it could be seen that the other side of the wing, viz., that gummed to the 

 glass, remained still yelloiv. 



t I was anxious to know whether or not it would be possible to restore the red 

 of Delias. I therefore touched it with a drop of acid, and then instantly washed 

 copiously with water : the result was a return of a faded washed-out red. Con- 

 sidering the rapid and easy solubility of the i^igment here, this was certainly &i 

 much as could bu expected. 



