Louse, in zoology, a genus of insects too well known to require any description.

Lice are not peculiar to mankind, but infest quadrupeds, birds, fishes, and vegetables. Each class of animals is troubled with a particular species of these vermin ; and birds are remarkably obnoxious to their attacks. There are forty different species of Ice that prey on the fluids of living animal bodies, and which are distinguished by their colour, shape, and size ; nay, even insects, such as snails, spiders, and bees, are not exempt from them.

The human race is liable to be exclusively invaded by three different species of lice; namely,. 1. The Crab, or Body-louse, which never appears in clothes, or on the head, but harbours only in some parts of the bodies of uncleanly, or such persons as are disordered by dissipation : it is easily exterminated, by applying a strong decoction of tobacco, or mercurial oint ment. 2. The Clothes-louse is larger than the next species, and has a thicker head; it visits the skin only for imbibing the necessary portion of its nourishment, when it retreats to the folds and scams of clothes : these vermin may be speedily destroyed by fumigating the articles of dress with sulphureous vapours. 3. The Head-louse frequents only that part of the body, and is ' so prolific, that each female,in the course of twelve days, deposits several hundred eggs, or nits, which are closely cement-, ed to the hair, and hatched in six or seven days, by warmth and perspiration : after three weeks, the young brood is fit for propagating their species; and as there are, perhaps, a hundred females to one male insect, their rapid increase maybe easily conceived.- Want of cleanliness; immoderate warmth;' Violent perspiration; and a corrupted state of the human fluids, remarkably promote their generation.—Among the most simple and harmless remedies for extirpating these vermin, is the seed of parsley reduced to a fine powder.—-But, if the humours of the whole animal body are in so vitiated a state, that the blood is contaminated by sen-sual excess of every kind, there arises the morbus pedicularis, .or the most dreadful of all diseases, in which those disgusting insects are bred in ulcers, and cover the whole frame, so that the ill-fated victim cannot be relieved.

Some constitutions, however, are more exposed to these odious Vermin than others ; and it is remarkable, that sea-faring men,performing voyages to the East Indies, though infested with them on leaving Europe, lose them in a certain degree of latitude during their Voyage; but, on their return, are again liableto their incursions.

Beside the remedies already sug-gested, we shall only observe, that in cases where danger is apprehended from lice, it will be useful to take nourishing, succulent food, and to use wholesome drink.- As. a cure for the pedicular' disease, Mercurialis advises frequent purgatives; at the same .time, to anoint the parts affected withi garlic and mustard ; to make use of salted and acid food ; to bathe, and to foment' the body with a decoction of gall-nuts ;- but the most effectual remedies are, sulphur and tobacco, mercurial ointment, black" pepper and vinegar.