tudes of sharp pins, almost like the quills of a porcupine. It has six legs, the joints of which are so adapted, that it can, as it were, fold them up one within another; and when it leaps, they all spring out at once, whereby its whole strength is exerted, and the body raised above two hundred times its own diameter.

The young fleas are at first a sort of nits or eggs, which are round and smooth; and from these proceed white worms, of a shining pearl colour: in a fortnight's time they come to a tolerable size, and are very lively and active; but if they are touched at this time, they roll themselves up in a ball soon after this, they begin to creep, like worms that have no legs; and then they seek a place to lie hid in, where they spin a silken thread from their mouth, and with it they inclose themselves in a small round bag or case, as white within as writing paper, but dirty without in this they continue for a fortnight longer; after which they burst from their confinement perfectly formed, and armed with powers to disturb the peace of an emperor.

[The Chigoe is the only other species of flea, This creature is well known to the inhabitants of many parts of America. Its size is so small as to be hardly perceptible, but its bite is attended with much more serious consequences than the irritating inhabitant of our own country. It pierces through the skin and flesh without its being felt, generally on the legs and toes, and gradually insinuating its head and body, completes its lodgment, and makes a nest of a thin white pellicle. In this nest it gradually dilates itself, and grows

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larger, feeding upon the disturbed humours of the body; and at last deposits its eggs, and forms a colony. If these are suffered to remain, till the tumour bursts, and the nits are hatched, an ulcer is formed, very difficult to heal, and which often eats down to the bone, causing a painful caries, often attended with the loss of the limb, and sometimes with the loss of life itself.]

CHAP. V.

Of the Louse, and its Varieties.

THE antipathies of mankind are various; some considering the toad, some the serpent, some the spider, and some the beetle, with a strong degree of detestation; but while all wonder at the strangeness of each other's aversions, they all seem to unite in their dislike to the Louse, and regard it as their natural and most nauseous enemy. Indeed, it seems the enemy of man in the most odious degree; for wherever wretchedness, disease, or hunger seize upon him, the louse seldom fails to add itself to the tribe, and to increase in proportion to the number of his calamities.

In examining the human louse with the microscope, its external deformity first strikes us with disgust the shape of the fore part of the head is somewhat oblong; that of the hind part somewhat

round the skin is hard, and being stretched, transparent, with here and there several bristly hairs: in the fore part is a proboscis or sucker, which is seldom visible on each side of the head are antennæ, or horns, each divided into five joints, covered with bristly hair; and several white vessels are seen through these horns behind these are the eyes, which seem to want those divisions observable in other insects, and appear encompassed with some few hairs: the neck is very short, and the breast is divided into three parts; on each side of which are placed six legs, consisting of six joints covered also with bristly hairs the ends of the legs are armed with two smaller and larger ruddy claws, serving these insects as a finger and thumb, by which they catch hold of such objects as they approach: the end of the body terminates in a cloven tail, while the sides are all over hairy; the whole resembling clear parchment, and, when roughly pressed, cracking with a noise.

When we take a closer view, its white veins, and other internal parts appear; as likewise a most wonderful motion in its intestines, from the transparency of its external covering. When the louse feeds, the blood is seen to rush, like a torrent, into the stomach; and its greediness is so great, that the excrements contained in the intestines are ejected at the same time, to make room for this new supply.

The louse has neither beak, teeth, nor any kind of mouth, as Doctor Hooke described it; for the entrance into the gullet is absolutely closed. In the place of all these it has a proboscis or trunk; or, as it may be otherwise called, a pointed hollow

sucker, with which it pierces the skin, and sucks the human blood, taking that for food only. The stomach is lodged partly in the breast and back; but the greatest portion of it is in the abdomen. When swoln with blood, it appears of a dark brown colour, which is visible through the skin; and is either a faint red, or a full or bright brown, as the contents of the stomach are more or less changed. When it is empty, it is colourless; but when filled, it is plainly discernible, and its motion seems very extraordinary. It then appears working with very strong agitations, and somewhat resembles an animal within an animal. Superficial observers are apt to take this for the pulsation of the heart; but if the animal be observed when it is sucking, it will then be found that the food takes a direct passage from the trunk to the stomach, where the remainder of the old aliment will be seen mixing with the new, and agitated up and down on every side.

If this animal be kept from food two or three days, and then placed upon the back of the hand, or any soft part of the body, it will immediately seek for food; which it will the more readily find, if the hand be rubbed till it grows red. The animal then turns its head, which lies between the two fore legs, to the skin, and diligently searches for some pore: when found, it fixes the trunk therein; and soon the microscope discovers the blood ascending through the head, in a very rapid, and even frightful stream. The louse has at that time sufficient appetite to feed in any posture; it is then seen sucking with its head downward, and its tail elevated. If, during this operation, the skin be drawn

tight, the trunk is bound fast, and the animal is incapable of disengaging itself; but it more frequently suffers from its gluttony, since it gorges to such a degree, that it is crushed to pieces by the slightest impression.

Whether lice are distinguished by the parts of generation into males and females, is not yet discovered Swammerdam is inclined to think that they are hermaphrodites, having found an ovary in all those he examined: and he dissected not less than forty-two. In one of these animals were found ten large eggs; and forty-four smaller, that were not yet come to their full perfection..

There is scarcely any animal that multiplies so fast as this unwelcome intruder. It has been pleasantly said, that a louse becomes a grand-father in the space of twenty-four hours: this fact cannot be ascertained; but nothing is more true than that the moment the nit, which is no other than the egg of the louse, gets rid of its superfluous moisture, and throws off its shell; it then begins to breed in its turn. Nothing so much prevents the increase of this nauseous animal, as cold and want of humidity; the nits must be laid in a place that is warm, and moderately moist, to produce any thing. This is the reason that many nits laid on the hairs in the night-time, are destroyed by the cold of the succeeding day; and so stick for several months, till they at last come to lose even their external form.

The louse is found upon every part of the human body but particularly in the heads of children. Those found upon the miners in Sweden are said,