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, &c., 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 microscope, or to inject them with some coloured fluid, by which their course, convolutions, and implications could be traced.
The insects 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 dissections consequently easier. When he had laid open with fine scissors the body of the insect, he carefully noted the relative situation of the parts before 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 opportunity of examining them. In this way he was very successful in getting a distinct view of the air-vessels
