In Paris, London, and many large towns, great numbers of Snails are frequently brought to market; but these are not employed as food, but used medicinally by persons suffering under consumption, and other diseases of the chest.
It was already known that polypi, and some species of worms, could have portions of their body cut off, and that the parts removed would be afterwards reproduced; and as these animals had no well distinguished extremities, such as heads or limbs, the fact, although singular, was not disputed; but, when it was asserted by Spallanzani, that Snails, which have a very well defined series of parts, could, after the head was removed, reproduce that portion of the body, the scientific world became naturally incredulous, and numerous experiments were made, and thousands of Snails slaughtered, to ascertain the fact. No one, however, for a length of time, could succeed;—it was then suspected that Spallanzani had only removed a portion of the head. At length, it would appear, from the experiments of M. G. Tarenne (an account of which appeared in 1808), that these creatures could actually reproduce a complete head. He gives as a reason of the want of success of others, the little precaution taken to provide the mutilated Snails with proper nourishment. The new head, according to him, is perfect in about two years after the old head has been removed.
M. Tarenne says, that after having cut off the heads of two hundred Snails, he threw them all into a moist spot at the end of his garden, that they might obtain the nourishment most fitted for them (how they could eat without their heads he does not say); at the end of the Summer he examined all the mutilated Snails he could find, and he discovered that they all had a new head, about the size of a grain of coffee; they had four small tentacula, a mouth, and lips; at the end of the following Summer, the heads were perfectly reproduced, and like the original head, with the exception of the skin, which was more delicate. “After this experiment,” says a French author, “we cannot doubt that the entire head of a Snail can be regenerated after it has been removed; however, I cannot disguise the fact, that I have a kind of repugnance at admitting the matter to be entirely beyond dispute.”
If the advantages bestowed on man by Snails are not numerous, the disadvantages, or rather inconveniences, produced by them are very considerable; they are particularly destructive in orchards and kitchen-gardens. On this account, many methods have been recommended for the purpose of destroying them. Although many of these are tolerably successful, there is no plan more likely to keep the breed of Snails under, particularly in enclosed gardens, than that of early rising and gathering them, if we may so express ourselves, while the dew is yet on the grass: if the shells are then broken, they become excellent food for poultry. Ducks may sometimes be allowed to wander in the garden, as they do but little damage to the vegetation, and are great destroyers both of Snails and slugs.
A singular account of the instinct of Snails is, perhaps, worth recording.
The garden of a small house, by the side of one of the roads leading into London, was much infested by a colony of Snails; the proprietor of this house, desirous of getting rid of the pest, and yet unwilling to kill the Snails, collected them, and threw them unharmed into the road; but still, he every morning discovered as many Snails among his pinks and tulips as he had removed the previous day; this somewhat puzzled him, until once, on leaving his house early, he perceived the Snails which he had but an hour before thrown into the dusty road, moving, not in a body, but each from the spot on which it was thrown, in a direct line from that spot to the low wall which encompassed the garden, as if they comprehended the mathematical fact that, “a straight line is the nearest way from one given point to another.” How were these Snails aware that by moving in that direction, they should arrive at a green spot? From the road nothing could be visible to them but dust,—from the path, nothing but the wall in front,—but still, although the whole of their path was covered with dust, they proceeded steadily on, until they had surmounted the wall, and reached their old quarters. By what other faculty were they guided but that instinct which supplies the place of the higher powers of the mind, and which is imparted with so liberal a hand to the meanest creature in nature?
ORDER GASTEROPODA.
The Gasteropods are so called from two Greek words, meaning belly and foot, because the foot, or organ of motion of the animals of which this order consists, is attached to the whole of the under part of the creature, or rather, the belly or under part is itself the foot, and is for that purpose broad and flat. The Gasteropods are also distinguished from the last order by having a straight body, in no case spiral, and never possessing a shell capable of enclosing the whole body; in some cases, the body is completely naked, and without the protecting covering of any shell whatever.
The Red Slug, ([Limax rufus].)
The Common Slug is a good example of an individual of this order, entirely wanting a shell. The Slugs, like the snails, are found in all countries; they are equally destructive to vegetation, but as yet have never been used by man for any useful purpose, if we except the fact of their sometimes becoming the food of ducks and poultry. The Limax rufus, Red, or more properly brown, Slug, for the colour is of a reddish-brown, varying in intensity to such an extent as to render it impossible to find two specimens of the same colour, is more commonly found in fields than in gardens.