56 
MEMOIR OF SWAMMERDAM. 
separate a membrane equably, without the laceration 
or disorder which a single edge, however sharp, is 
apt to produce in delicate substances. These, as 
well as his variously formed knives, lancets, styles, 
ike., were so small and fine, that he could not sharpen 
them without the aid of a microscope. He employed 
to very great advantage, and with a dexterity entirely 
his own, slender glass tubes, sometimes no thicker 
than a bristle, and of a similar shape, being wide at 
the one end and tapering to a point at the other, to 
blow up the smallest vessels discovered by the micro- 
scope, or to inject them with some coloured fluid, by 
which their course, convolutions, and implications 
could be traced. 
The iusects designed for dissection were killed by 
immersion in water, spirits of wine, or of turpentine, 
and allowed to remain in some one or other of these 
substances for some time, which prevented putridity, 
rendered the parts firmer and stronger, and the dis- 
sections consequently easier. When he had laid 
open with fine scissors the body of the insect, he 
carefully noted the relative situation of the parts be- 
fore proceeding farther ; he then extracted the viscera 
in a very leisurely and cautious manner, separating 
and washing away with very fine camel’s-hair pencils 
the fat which surrounds them. After extraction he 
frequently floated the delicate viscera in water, and, 
by shaking them gently, separated the different parts 
from each other, and thus obtained a better oppor- 
tunity of examining them. In this way he was very 
successful in getting a distinct view of the air-vessels 
