BOOK VI. WORMS. THESE creatures constitute a class by themselves, under the name of Vermes, in the voluminous works of nomenclators. They are generally divided into five orders, which embrace the whole of those innumerable tribes that swarm nearly every where. The Worm is distinguished from the caterpillar and maggot, on account of its undergoing no change, and crawling by means of the annular structure of its body. The Earth Worm has neither bones, eyes, ears, nor brains; it has a round, annulated body, with generally an elevated fleshy belt near, the head. Though considered a great nuisance by gardeners, they bore, perforate, and loosen the soil, and render it pervious to rains and the fibres of plants, by drawing straws and stalks of leaves and twigs into it; and chiefly by throwing infinite numbers of lumps called worm-casts, which form a fine manure for grass and corn. The Tania, or Tape-Worm, the shape of which is well expressed by its name, is bred in the inside of animals, and principally in the bowels of the human species. Its body is flat, and composed of numerous articulations; and the head has four orifices for suction, a little below the mouth, which is terminal, and continued by a short tube into two ventral canals. The mouth is generally crowned with a double series of retractile hooks or holders. The author of these observations extracted, a few years ago, a Tape-Worm from the body of a ring-dove, to the length of more than three feet, at different times. The bird did not seem to labour under any uneasiness, although it lodged and boarded within itself so voracious and disagreeable a guest. Is about three inches in length, and in its exterior form somewhat resembles the worm, when extended, but often contracts itself greatly in length, and at the same time expands in breadth. It has a small head, a black skin, with six yellow lines above, and spotted with yellow on the belly. The mouth of the Leech is of a curious construction; it has no jaws or tongue, but three cartilaginous teeth, with which it pierces the skin; and then draws up, as through a siphon, the blood, which this small animal feeds upon. The progressive movement of the Leech is effected by sticking, through suction, its mouth to a certain spot, then bringing its tail, which has the property of sticking also, to any place, ever so smooth, and then advancing its head farther on, quickly followed by the tail, and so on. The common Leech is very frequent in brooks and rivulets; and often sticks to the legs of boys or men when bathing. The blood, which the Leech sucks out of the wound it makes, remains long in its body, congealed and blackened, and at last evaporates by the pores of the skin. When they are kept in a bottle full of water, it is easily perceived that their ejections are performed by perspiration, and leave the skin as a kind of film, bearing in some sort the shape of the body. They are also, when kept in a glass bottle with water, a good barometer, as they always come up to the neck of the bottle when rainy weather is approaching, remain in the bottom in dry weather, and move themselves anxiously up and down when the weather is stormy.Horse Leeches are larger than the common ones, more voracious, and narrower at each extremity. The use of the Leech is well known in medicine, as by its means the blood is extracted from diseased parts, to which the lancet cannot be applied. Is furnished with four small horns; two of which are smaller than the others; at the end of these horns, which the animal pushes out or draws back, like telescopes, as most convenient to itself, are the eyes, which look like black spots, one upon each of the horns; and it is probable that the extending or contracting of these tubes is in proportion to the size or distance of the object which the animal wishes to see. The mouth is under the two smaller ones; and is armed with eight teeth, to enable it to devour leaves and other vegetable substances, its ordinary food. The reproduction of the Snail is most curious; at a certain time of the year they meet in pairs, and stationing themselves an inch or two apart, they launch at each other several little darts, not quite half an inch long. These are of a horny substance, and sharply pointed at one end. The animals, during the breeding season, are furnished with a little reservoir for them, situated in the neck, and opening on the right side. After the discharge of the first dart, the wounded Snail immediately retaliates on its aggressor by ejecting at it a similar one; the other renews the battle, and in turn is again wounded. Thus are the darts of Cupid, metaphorical with all the rest of the creation, completely realized in Snails. After the combat they come together, each of them lays its eggs, which are about the size of small peas, semitransparent, and of a soft substance. We have observed the process of the eggs which a Water Snail, kept in a bottle of water, had deposited against the glass; with the help of a magnifying lens, the young Snail was seen in the egg, with its embryo shell on its back; we observed also two in one egg, each of them with the rudiments of the shell. The Garden Snail is extremely tenacious of life, and the following well authenticated instance is probably without parallel in any other individuals in the animal creation. Mr. S. Simon, a merchant of Dublin, whose father, a fellow of the Royal Society, and a lover of natural history, left him a small collection of fossils and other curiosities, had, among them, the shells of some Snails. About fifteen years after his father's death (in whose possession they had continued many years), he gave to his son, a child of ten years old, some of these Snail-shells to play with. The boy placed them in a flower-pot, which he filled with water, and the next day he put them into a basin. Having occasion to use this, Mr. Simon observed that the animals had U 3 He examined the child The boy said he come out of their shells. respecting them; and was assured that they were the same which had been in the cabinet. had a few more, and brought them. Mr. S. put one of these into water, and, in an hour and a half afterwards, he observed that it had put out its horns and body, which it moved but slowly, probably from weakness. Major Vallancy, Dr. Span, and other gentlemen, were afterwards present, and saw one of the Snails crawl out; the remainder being dead, probably from their remaining some days in the water. The Small Gray Slug is a Snail without shell, and resembles it in all other points, except that the brown skin of the back is rougher and stronger than in the Snail. Its progress on the ground may easily be traced by the slime which it leaves in its track. Few animals are more destructive to vegetation than these. The Black Slug is a well known inhabitant of our fields and meadows, during the summer season. The country people consider the appearance of this Slug as an indication of approaching rain; but this is rather to be accounted for by the moisture of the ground and of the plants. It is very seldom, indeed, to be observed abroad during dry weather, for this would deprive the external parts of its body of the moisture which is requisite for its subsistence. The Black Slug feeds on the leaves of different kinds of plants. The Slug is an emblem of tardiness and slowness; and our immortal Shakspeare introduces the Snail very appropriately in his description of the Seven Ages of Man; when he says, And then the whining schoolboy, with his satchel |