INTERNAL ANATOMY ‘OF INSECTS. 195 
by which means the vessels become firmer and stronger. 
The parts of pupe 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 Lyonnet, 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 care- 
fully divided longitudinally with scissors, should if flexi- 
ble 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 observations 
as present themselves without further dissection, the vis- 
cera 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 se- 
paration 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 patience of 
Swammerdam, you may even arrive at injecting 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 dis- 
solved, he succeeded in preserving them. If it is not 
convenient fo finish the dissection of an insect at once, 
it should be covered with spirits of wine. Swammerdam 
found a mixture of spirits and distilled vinegar very use- 
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