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SEVENTH WEEK-FRIDAY.

HYBERNATION OF THE SNAIL.

THE garden-snail has its congeners in the waters, which, in outward appearance, bear a striking resemblance to it; but its habits and instincts are quite different from those of the same genus in another element. It is admirably adapted to its mode of life, and is furnished with organs almost as complete as the largest animal; with a tongue, brain, salival ducts, glands, nerves, stomach, and intestines; with liver, heart, and bloodvessels. These it possesses in common with other animals, but it has some striking peculiarities,—one of which is, that, of four flexible horns with which it is furnished; the two uppermost are gifted with eyes, which appear like black spots on their extreme ends, and which it can hide, by a very swift contraction, in the interior of its body. Every one knows, that another peculiarity which distinguishes it from other land animals, is its shell, which it carries on its back wherever it goes, and which serves at once as its house for lodging, and as its armour for defence.

The history of this animal, so far as it suits our present purpose to advert to it, is as follows:-Each individual snail is both a father and a mother; and it lays its eggs in shady and moist hollows, which it excavates with a member which is called its foot, as by this it has the power of locomotion. These eggs are hatched, sooner or later, according to the temperature, producing little snails, exactly resembling their parent, but so delicate, that a sun-stroke destroys them, so that few, comparatively speaking, reach the end of the first year, when they are sufficiently defended by the hardness of their shell. The animal, at its first exclusion, lives solely on the pellicle of the egg from which it was produced. "Providence," as Kirby justly observes, "which, in oviparous and other animals, has provided for the first nu

triment of the young in different ways, appropriating the milk of the mother to the young of quadrupeds, the yolk of the egg to those of birds, tortoises, and lizards, and the white of the egg to frogs and toads, has made this pellicle, or coat, the best nutriment of the young snail. In fact, this pellicle, consisting of carbonate of lime, united to animal substance, is necessary to produce the calcareous secretion of the mantle, and to consolidate the shell, as yet too soft for exposure." When this natural envelope is eaten, the young snail finds its nourishment in the vegetable soil around it. After the concealment of a month, it appears on the vegetable productions of the garden or meadow, which it seems indiscriminately to devour,—its house still growing with its growth, till it has completed five convolutions, by which time the animal has attained its full size.

These snails cease feeding when the first chills of autumn are felt; and, generally associating in considerable numbers, on hillocks, in the banks of ditches, or in thickets and hedges, they set about their preparations for their winter retreat. They first expel the contents of their intestines, and then, concealing themselves under moss, grass, or dead leaves, each forms, by means of its foot, and the viscid mucus which it secretes, a cavity large enough to contain its shell. The mode in which it effects this is remarkable; collecting a considerable quantity of the mucus on the sole of its foot, a portion of earth and dead leaves adheres to it, which it shakes off on one side; a second portion is again collected and deposited, and so on, till it has reared around itself a kind of wall, of sufficient height to form a cavity that will contain its shell; and then, by turning itself round, it presses against the sides, which renders them smooth and firm. The dome, or covering, is formed in the same way; earth is collected on the foot, which it then turns upward, and throws off by exuding fresh mucus; and this is repeated, till a perfect roof is formed. Having now completed its winter house, it draws in its foot, co

vering it with the mantle, and opens its spiracle to draw in the air. On closing this, it forms, with its slime, a fine membrane, interposed between the mantle and extraneous substances. Soon afterwards, the mantle secretes a large portion of very white fluid over its whole surface, which instantly sets uniformly, and forms a kind of solid operculum, like plaster of Paris, about half a line in thickness, which accurately closes the mouth. When this is become hard, the animal separates the mantle from it. After a time, expelling a portion of the air it had inspired, and thus being reduced in bulk, it retreats a little further into the shell, when it forms another leaf of mucus; and it continues repeating this operation, till there are sometimes five or six of these leaves, forming cells filled with air between it and the operculum. Respiration ceases during the period of hybernation.*

The mode in which these animals escape from their winter confinement is singular:-The air which they had expired, on retiring into their shell farther and farther, remains between the different partitions of the mucous membrane above mentioned, which forms so many shells hermetically sealed ;—this they again inspire, and thus acquiring fresh vigour, each separate partition, as they proceed, is broken by the pressure of the foot, projected in part through the mantle ;-when arrived at the operculum, they burst in by a strong effort, and finally detaching it, then emerge, begin to walk, and to break their long fast!

"In all these proceedings," observes Mr Kirby, after recording the above details, "the superintending care and wise provisions of a Father-Being are evident. This creature can neither foresee the degree of cold to which it may be exposed in its state of hybernation, nor know by what means it may secure itself from the fatal effects it would produce upon it, if not provided against.

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But, at a destined period, often when the range of

* Goldsmith is mistaken when he says, that the snail opens an air-hole into its shell. Gaspard and Bell; Zoological Journal, i. 93; ii. 174.

the thermometer is high, not stimulated by a cold atmosphere, except perhaps by the increasing length of the night,—at the bidding of some secret power, it sets about erecting its winter dwelling; and, employing its foot, not only as a shovel to make its mortar, but as a hod to transport it, and a trowel to spread it duly and evenly, at length finishes and covers in its snug and warm retreat; and then, still farther to secure itself from the action of the atmosphere, with the slimy secretion with which its Maker has gifted it, fixes partition after partition, and fills each cell, formed by it, with air, till it has retreated as far as it can from every closed orifice of its shell, and thus barricades itself against a frozen death. Again, in the spring, when the word is spoken,—Awake, thou that sleepest, it begins immediately to act with energy; it re-inspires, as above related, the air stored in its cells; bursts all its cerements; returns to its summer haunts, and again lays waste our gardens.”

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SEVENTH WEEK-SATURDAY.

HYBERNATION OF THE BEETLE. ANIMALCULES IN PASTE.

AMONG insects, the beetle has some peculiar instincts, which will come more properly under our observation at another season. At present, I shall only mention three instances of remarkable habits relating to the state of particular species of this insect in winter. Beetles, it may be premised, are distinguished from other tribes of the same order, by being furnished with cases to cover two transparent wings. Like other insects, they are bred from eggs, which first become grubs; then chrysalides, in which parts of the future fly are distinctly seen; and, lastly, assuming their perfect or imago state, they acquire wings, and mount into the air.

The first species of this little animal which I shall introduce to the notice of my readers, is the May-bug, or Kirby's Bridgewater Treatise, pp. 285-289.

Dorr-beetle, well known to children by its evening buzz during the months of summer. In its maggot state, in which it remains, without any other change than increase of size and the annual renewal of its skin, for no less a period than three years, it burrows under ground, so near the surface, as to devour the roots of plants, on which it feeds voraciously, and without discrimination. When largest, it is found an inch and a half long, of a whitishyellow colour, with a body consisting of twelve segments or joints, on each side of which there are nine breathing holes, and three red feet; but it is destitute of eyes, having no occasion for them in its natural habitation, where light does not penetrate,—here exhibiting a new and remarkable instance of the attention of the Creator, in adapting the faculties of creatures to the situation for which they are destined, as well in what he withholds as in what he grants.

At the end of the fourth year of its existence, it begins to provide itself a secure winter habitation, with a view to its future condition. About the latter end of August, it seems first to come under the influence of that extraordinary instinct, which leads it to prepare for its important change. It then buries itself deeper and deeper in the earth, sometimes, in favourable situations, to the depth of six feet, and there forms for itself a capacious apartment, the walls of which it renders very smooth and shining, by the exertions of its body. Its abode being thus formed, it begins soon after to shorten itself, to swell, and to burst its last skin, in order to assume the form of a chrysalis. This, in the beginning, appears of a yellowish colour, which heightens by degrees, till at last it appears nearly red. Its exterior form plainly discovers all the vestiges of the future winged insect, the entire fore-parts being distinctly seen; while, behind, the animal seems as if wrapped in swaddling-clothes.

The young May-bug continues in this state for nearly three months, and then divests itself of all its impediments, and becomes a winged insect, completely formed.

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