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 Libellulz), 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 
