202 INTERNAL ANATOMY OF INSECTS. 
by which means the vessels become firmer and stronger. 
The parts of pup<r become much more distinct if they 
are boiled for a few minutes : and the same mode may 
be adopted in the examination of spiders. 
The most convenient mode of proceeding, which was 
that also of Lyonet, is to dissect the insect in water, or, 
to avoid putridity, in diluted spirits, — if small, upon a 
concave glass, to which it should be fastened by means 
of a little melted wax; if larger, in the bottom of a com- 
mon chip box, surrounded with a border of wax to re- 
tain the fluid. The integuments of the insect, being 
carefully divided longitudinally with scissors, should if 
flexible be turned back, and fixed by small pins stuck in 
by a fine pair of pliers, while the skin at the same time 
is stretched by another. After making such observa- 
tions as present themselves without further dissection, 
the viscera must be cautiously extracted, washing away 
the fat which surrounds them with spirits of turpentine, 
in which it is soluble, applied by camel's-hair pencils. 
After separation they may conveniently be examined by 
putting them into water, and gently shaking them so as 
to cause the parts to unfold. If endowed with the pa- 
tience of Swammerdam, you may even arrive at inject- 
ing these minute parts with wax or coloured fluids, 
conveyed by delicate glass tubes having one end as fine 
as a hair, which he also employed to fill the viscera 
with air; and afterwards drying them in the shade, and 
anointing them with oil of spike in which a little resin 
had been dissolved, he succeeded in preserving them. If 
it is not convenient to finish the dissection of an insect 
at once, it should be covered with spirits of wine. Swam- 
merdam found a mixture of spirits and distilled vinegar 
