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 
I recommended above, "cannot be applied to the 
outside of most insects (especially Libellulee), 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 
(nade in the colours of insects. Those colours 
j ivhich originate from without, as in the moths and 
I Dutterflies, remain unimpaired in pristine splendour 
ifter death, until they are destroyed by force or by 
iccident. On the other hand, those colours which 
nave their source from within, and proceed from 
noist substances, gradually fade after the death of 
he insect; and, in some cases, even totally disap- 
pear, when the substances from which they drew 
heir origin have become dry and hard. By long 
ixperience, I know that the colours of insects which 
ire produced internally, as in the red dragon fly of 
