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body is long, depressed, and consists of numerous transverse segments, each of which is furnished with a pair of legs.

THE GREAT CENTIPEDE *.

None of the Insect tribe, the Scorpions excepted, are so formidable in appearance as the Centipede. It is found in the East and West Indies, and in various parts of Africa, inhabiting chiefly the woods, where it is preyed upon by the different species of snakes. It is, however, sometimes found in houses, and is said to be so common in particular districts, that the inhabitants are obliged to have the feet of their beds placed in vessels of water, in order to prevent their being annoyed during the night by these horrible reptiles.

Gronovius says, that all the legs of this animal are venomous; but its most formidable weapons are the two sharp and hooked instruments, that are placed under the mouth, with which it destroys its prey. At the extremity of each of these there is a small opening, through which it is supposed the Centipede emits the poisonous fluid into the wound inflicted by the fangs.

Leeuwenhoek, desirous of ascertaining some facts relative to the poison emitted by the Centipede, placed a large fly within the reach of one of these animals. He seized it between a pair of the middle feet, then passed it from one pair to the next, till it was brought under the fangs; which were plunged into its body,

* DESCRIPTION. The Great Centipedes vary much both in size and colour. Some of them are of deep reddish brown, others of a yellow ochre colour, livid yellow, or tinged with red; and they are sometimes seen more than a foot in length. Their legs terminate in very sharp hooks, or nails, of a shining black colour.

SYNONYMS. Scolopendra morsitans. Linn.-Great Scolopendra. Shaw's Nat. Mis.-Centipee, in the West Indies.La Scolopendre mordante. Tigny.

and it died instantly. M. St. Pierre says, that, in the Isle of France, his dog was bitten by a Centipede upwards of six inches in length, and that the wound be came ulcerous, and was three weeks in healing. He was highly diverted in observing one of these animals overcome by a vast number of ants, that attacked it in conjunction, and, after having seized it by all its legs, bore it along, as workmen would have done a large piece of timber. The poison of the Centipede is not more injurious than that of the scorpion, and seldom proves fatal to the larger animals.

Some of the American Indians eat Centipedes.

WORMS*.

Intestinal Worms +.

OF THE ASCARIDES IN GENERAL.

ALTHOUGH these worms have long been known to inhabit the stomach and intestines of men and animals, their origin and history seem enveloped in great obscurity. The difficulty of making satisfactory observations, and the want of favourable circumstances under which to attend to them, have hitherto presented insuperable obstacles to an intimate knowledge of their habits and economy.

In structure they are very simple, for, being intended to subsist on already-digested food, they are not furnished with any complicated organs. The denomination of Ascaris has been given to them from the circumstance of their being almost constantly in motion §.

Some of the species are oviparous, and others produce living offspring.

* For an account of Worms in general, see vol. i. p. 46. + In the Linnean order of Intestina, the animals are simple, naked, and without limbs.

The bodies of these Worms are cylindrical, semi-transparent, and slender at each extremity. The head is furnished with three small vesicles. The intestines are generally spiral, and of a whitish colour.

§ From the Greek word asxapılır, salire.

*

THE LUMBRICAL AND VERMICULAR ASCARISt.

In the intestines of thin persons, the former of these Worms are frequently found. They are most abundant about the ileum, but they sometimes ascend into the stomach, and even creep out at the mouth and nostrils. It does not often happen that they descend into the large intestines, except on the exhibition of medicines which increase the action of the intestines. When very numerous, they give rise to unpleasant, and sometimes even to fatal disorders.

They are supposed to fix themselves by three tubercles at the anterior extremity of their body, whilst, through a small triangular aperture, situated in the centre, betwixt these tubercles, they suck the nutritive juices on which they are supported. Their interior organization appears to consist only of a simple intestine, composed of a fine and very delicate membrane, which is always filled with an orange-coloured liquor.

The motion of these Worms is serpentine, and in no respect resembles that of the Earth-worm, with which they have sometimes been ignorantly confounded. The latter has the power of contracting and extending its body, whilst the length of the Ascaris is never diminished. The head is always thrown forward, by the Worm curling itself into circles, and suddenly extend

* DESCRIPTION. The length of the Lumbrical Ascaris, is from twelve to fifteen inches. Its body is semi-transparent, and of a light yellow colour. The head is slightly incurved, with a transverse contraction beneath; and the mouth is triangular.

SYNONYMS. Ascaris lumbricoides, Linn.-Ascaride lombrical. Bosc, Cuvier.

+ DESCRIPTION. This Worm is usually about half an inch in length, somewhat dilated in the middle of the body, and wrinkled at the sides. The head is subulate, and the tail tapers to a fine point. It is of a whitish colour. Linn.-Ascaride ver

SYNONYMS. Ascaris vermicularis. miculaire. Bosc. Cuvier.

ing its head with considerable force. These worms are oviparous.

The Vermicular Ascarides are very common in the intestines of children; and are sometimes found in the stomach. Their number exceeds all calculation, and they cause a most unpleasant sensation of itching, by piercing the skin in a slight degree, with their awlshaped tails. Even newly-born children are not always free from them.

They are viviparous. The female has, at the distance of about an eighth of an inch from the head, a small punctiform aperture, through which the offspring are protruded. Dr. Hooper, in the Memoirs of the Medical Society of London, informs us, that he has seen upwards of a hundred young-ones escape through this aperture, all alive, and vivacious several hours after the death of the mother.

The present species are sometimes known by the appellation of man or thread-worms.

OF THE FASCIOLÆ, OR FLUKE-WORMS.

Fluke-worms are often very numerous in the viscera of quadrupeds, birds, fishes, and reptiles. They are found in the stomach, the intestines, and the liver. Each individual has both the sexes united in itself. They are oviparous, and the ovaries are lateral.

Their body is oblong and flattish, and is furnished with two orifices, one of which is situated at the anterior extremity of the body, and the other at a little distance beneath it. The interior represents an intestinal canal, which, after passing round the body, folds upon itself, and terminates at the second orifice.

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