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The Louse

devouring them. Numbers of little red lice, with a very small head, and in shape resembling a tortoise, are often seen about the legs of spiders, and they never leave the animal while he lives; but if he be killed, they almost instantly forsake him. A sort of whitish lice is found on humblebees; they are also found upon ants; and fishes are not less subject to them than other animals. Kircher tells us, that he found lice also on flies, and M. de la Hire has given a curious account of the creature which he found on the common fly. Having occasion to view a living fly with the microscope, he observed on its head, back, and shoulders, a great number of small anithe mals crawling very nimbly about, and often climbing up hairs which grow at the origin of the fly's legs. He with a fine with a fine needle took up one of these, and placed it before the microscope used to view the animalcules in fluids. It had eight legs, four on each side; these were not placed very distant from each other, but the four towards the head were separated by a small space from the four towards the tail. The feet were of a particular structure, being composed of several fingers, as it were, and fitted for taking fast hold of any thing, but the two nearest the head were also more remarkable in this particular than those near the tail; the extremities of the legs for a little way above the feet were dry, and void of flesh, like the legs of birds, but above this part they appeared plump and fleshy. It had two small horns upon its head, formed of several hairs arranged closely together; and there were some other clusters of hairs by the side of these horns, but they had not the same figure; and towards the origin of the hind-legs there were two other such clusters of hairs, which took their origin at the middle of the back. The whole creature was of a bright yellowish red; the legs, and all the body, except a large spot in the centre, were perfectly transparent. In size, he computed it to be about th part of the head of the fly; and he observes, that such kind of vermin are rarely found on flies.

The louse which infests the human body, makes a very curious appearance through a microscope. It has such a transparent shell or skin, that we are able to discover more of what passes within its body, than in most other living creatures. It has naturally three divisions, the head, the breast, and the tail part. In the head appear two fine black eyes, with a horn that has five joints, and is surrounded with hairs standing before each eye; and from the end of the nose, or snout, there is a pointed projecting part, which serves as a sheath or case to a piercer, or sucker, which the creature thrusts into the skin to draw out the blood and humours which are its destined food; for it has no mouth that opens in the common way. This piercer, or sucker, is judged to be 2 T •