PRESERVING INSECTS. 75 



admiration of future ages, may fall a prey to an in- 

 truding and almost invisible enemy ; so that, unless 

 he apply the solution of corrosive sublimate in alco- 

 hol, he is never perfectly safe from a surprise. I 

 have tried a decoction of aloes, wormwood, and wal- 

 nut leaves, thinking they would be of service, on 

 account of their bitterness: the trial completely 

 failed. Wherefore, in conclusion, I venture to re- 

 commend the preserver of insects not to put much 

 trust in simples. 



" Contra vim mortis, non est medicamen in hortis." 

 Against the deadly moth, can I, 

 From herbs, no remedy supply. 



It having been stated that the solution I have 

 recommended above, "cannot be applied to the 

 outside of most insects (especially Libellulae), with- 

 out, in course of time, injuring their colours," I 

 request attention to the few following observ- 

 ations : There are two grand distinctions to be 

 made in the colours of insects. Those colours 

 which originate from without, as in the moths and 

 butterflies, remain unimpaired in pristine splendour 

 after death, until they are destroyed by force or by 

 accident. On the other hand, those colours which 

 have their source from within, and proceed from 

 moist substances, gradually fade after the death of 

 the insect ; and, in some cases, even totally disap- 

 pear, when the substances from which they drew 

 their origin have become dry and hard. By long 

 experience, I know that the colours of insects which 

 are produced internally, as in the red dragon fly of 



