CHAP. XVIII.

CURIOSITIES RESPECTING SERPENTS AND WORMS.

_The Scorpion--The Boa Constrictor--The American Sea Serpent-- Fascinating Serpents--The Caterpillar--Caterpillar-Eaters--The Silk-Worm--The Tape-Worm--The Ship-Worm--The Lizard imbedded in Coal._

THE SCORPION.

Their flaming crests above the waves they shew, Their bellies seem to burn the seas below; Their speckled tails advance to steer their course, And on the sounding sh.o.r.e the flying billows force.

And now the strand and now the plain they held; Their ardent eyes with b.l.o.o.d.y streaks are fill'd; Their nimble tongues they brandish'd as they came, And lick'd their hissing jaws that sputter'd flame.

_Dryden._

Of all the cla.s.ses of noxious insects, the scorpion is the most terrible.

Its shape is hideous; its size among the insects is enormous; and its sting is generally fatal. Happily for Britain, the scorpion is entirely unknown among us. In several parts of the continent of Europe, it is too well known, though it seldom grows above four inches long; but in the warm tropical climates, it is seen a foot in length, and in every respect as large as a lobster, which it somewhat resembles in shape. There have been enumerated nine different kinds of this dangerous insect, including species and varieties, chiefly distinguished by their colour; there being scorpions yellow, brown, and ash-coloured; others that are the colour of rusty iron, green, pale yellow, black, claret colour, white, and gray.

There are four princ.i.p.al parts distinguishable in this creature; the head, the breast, the belly, and the tail. The scorpion's head seems, as it were, jointed to the breast, in the middle of which are seen two eyes; and a little more forward, two eyes more, placed in the fore part of the head; these eyes are so small, that they are scarcely perceivable, and it is probable the creature has but little occasion for them. The mouth is furnished with two jaws; the undermost is divided into two, and the parts notched into each other, which serve the creature as teeth, and with which it breaks its food, and thrusts it into its mouth; these the scorpion can at pleasure pull back into its mouth, so that no part of them can be seen.

On each side of the head are two arms, each composed of four joints; the last of which is large, with strong muscles, and made in the manner of the claw of a lobster. Below the breast are eight articulated legs, each divided into six joints; the two hindmost of which are each provided with two crooked claws, here and there covered with hair. The belly is divided into seven little rings; from the lowest of which is continued a tail, composed of six joints, which are bristly, and formed like little globes; the last being armed with a crooked sting. This is that fatal instrument which renders this insect so formidable; it is long, pointed, hard, and hollow; it is pierced near the base with two small holes, through which, when the creature stings, it ejects a drop of poison, which is white, caustic, and fatal. The reservoir in which this poison is kept, is a small bladder near the tail, into which the venom is distilled by a peculiar apparatus. If this bladder be greatly pressed, the venom will be seen issuing out through the two holes above mentioned; it therefore appears, that when the creature stings, the bladder is pressed, and the venom issues through the two apertures into the wound.

There are few animals more formidable, or more truly mischievous, than the scorpion. As it takes refuge in a small place, and is generally found sheltering in houses, it must frequently sting those among whom it resides. In some of the towns of Italy, and in France, in the ci-devant province of Languedoc, it is one of the greatest pests that torment mankind; but its malignity in Europe is trifling, when compared to what the natives of Africa and the East are known to experience. In Batavia, where they grow twelve inches long, there is no removing any piece of furniture without the utmost danger of being stung by them. Bosman a.s.sures us, that along the Gold Coast they are often found larger than a lobster, and that their sting is inevitably fatal.

In Europe, however, they are by no means so large, so venomous, or so numerous. The general size of this animal does not exceed two or three inches, and its sting is very seldom fatal. No animal in the creation seems endued with such an irascible nature; they have often been seen, when taken and put into a place of security, to exert all their rage against the sides of the gla.s.s vessel that contained them. They will attempt to sting a stick when put near them, and attack a mouse or a frog, while these animals are far from offering any injury. Maupertuis put three scorpions and a mouse into the same vessel together, and they soon stung the little animal in different places. The mouse, thus a.s.saulted, stood for some time upon the defensive, and at last killed them all, one after another. He tried these experiments, in order to see whether the mouse, after it had killed, would eat the scorpions; but the little quadruped seemed satisfied with the victory, and even survived the severity of the wounds it had received.

Wolkemar tried the courage of the scorpion against the large spider, and inclosed several of both kinds in gla.s.s vessels for that purpose. The success of this combat was very remarkable. The spider at first used all his efforts to entangle the scorpion in his web, which it immediately began spinning; but the scorpion rescued itself from the danger, by stinging its adversary to death; and soon after cut off, with its claws, all the legs of the spider, and then sucked all the internal parts at its leisure. If the scorpion's skin had not been so hard, Wolkemar is of opinion that the spider would have obtained the victory; for he had often seen one of these spiders destroy a toad.

The fierce spirit of this animal is equally dangerous to its own species, for scorpions are the cruellest enemies to each other. Maupertuis put about a hundred of them together in the same gla.s.s; and they scarcely came in contact before they began to exert all their rage in mutual destruction: there was nothing to be seen but one universal carnage, without any distinction of age or s.e.x; so that in a few days there remained only fourteen, which had killed and devoured all the rest. But their unnatural malignity is still more apparent, in their cruelty to their offspring. He inclosed a female scorpion, big with young, in a gla.s.s vessel, and she was seen to devour them as fast as they were excluded; there was but one of the number that escaped the general destruction, by taking refuge on the back of its parent; and this soon after revenged the cause of its brethren, by killing the old one in its turn. Such is the terrible and unrelenting nature of this insect, that it is a.s.serted, when driven to an extremity, that the scorpion will even destroy itself. The following experiment was ineffectually tried by Maupertuis: "But (says Mr.

Goldsmith) I am so well a.s.sured of it by many eye-witnesses, who have seen it both in Italy and America, that I have no doubt remaining of its veracity. A scorpion newly caught is placed in the midst of a circle of burning charcoal, and thus an egress prevented on every side; the scorpion, as I am a.s.sured, runs about a minute round the circle, in hopes of escaping, but finding that impossible, it stings itself on the back of the head, and in this manner the undaunted suicide instantly expires."

It is happy for mankind that these animals are so destructive to each other; since otherwise they would multiply in so great a degree as to render some countries uninhabitable. The male and female of this insect are very easily distinguishable; the male being smaller, and less hairy.

The female brings forth her young alive, and perfect in their kind. Redi having bought a quant.i.ty of scorpions, selected their females, and, putting them in separate gla.s.s vessels, kept them for some days without food. In about five days one of them brought forth thirty-eight young ones, well shaped, and of a milk-white colour, which changed every day more and more into a dark rusty hue. Another female, in a different vessel, brought forth twenty-seven of the same colour; and the day following, the young ones seemed all fixed to the back and belly of the female. For near a fortnight all these continued alive and well, but afterwards some of them died daily; until, in about a month, they all died, except two. Were it worth the trouble, these animals might be kept living as long as curiosity should think proper. Their chief food is worms and insects; and upon a proper supply of these, their lives might be lengthened to their natural extent: how long that may be we are not told; but, if we may argue from a.n.a.logy, it cannot be less than seven or eight years, and perhaps, in the larger kind, double that duration. As they have somewhat the form of a lobster, so they resemble that animal in casting their sh.e.l.l; or, more properly, their skin, since it is softer by far than the covering of the lobster, and set with hairs, which grow from it in great abundance, particularly at the joinings. The young, prior to their birth, lie each covered up in its own membrane to the number of forty or fifty, and united to each other by an oblong thread, so as to exhibit altogether the form of a chaplet.

Such is the manner in which the common scorpion produces its young; but there is a scorpion of America, produced from the egg, in the manner of the spider. The eggs are no larger than pin's points; and they are deposited in a web, which they spin from their bodies, and carry about with them till they are hatched. As soon as the young ones are excluded from the sh.e.l.l, they get upon the back of the parent, who turns her tail over them, and defends them with her sting. It seems probable, therefore, that captivity produces that unnatural disposition in the scorpion, which induces it to destroy its young; since, at liberty, it is found to protect them with such unceasing a.s.siduity.

Another subject of curiosity belonging to this cla.s.s, is, THE BOA CONSTRICTOR.--A serpent very remarkable for its vast size; some of the princ.i.p.al species of which are met with in India, Africa, and South America, and have been seen between thirty and forty feet long, possessed of so much strength as to be able to kill cattle by twisting around them, and crushing them to death by pressure, after which they devour them, eating till they are almost unable to move; and in that state they may be easily shot. Dr. Shaw observes, that these gigantic serpents are become less common, in proportion to the increased population of the parts where they are found; they are, however, still to be seen, and they will approach the abodes of man in the vicinity of their residence. This species is beautifully variegated with rhombic spots; the belly is whitish; it is of vast strength, and from thirty to thirty-six feet long.

With respect to age, s.e.x, and climate, it is subject to great variations.

It is supposed that an individual of this species once diffused terror and dismay through a whole Roman army; a fact alluded to by Livy in one of the books that have not come to us, but which is quoted by Valerius Maximus, in words to the following effect: "Since we are on the subject of uncommon phenomena, we may here mention the serpent so eloquently recorded by Livy, who says, that near the river Bagrada, in Africa, a snake was seen of such enormous magnitude, as to prevent the army of Attilius Regulus from the use of the river; and after s.n.a.t.c.hing up several soldiers with its enormous mouth, and devouring them, and killing several more by striking and squeezing them with the spires of its tail, it was at length destroyed by a.s.sailing it with all the force of military engines and showers of stones, after it had withstood the attack of their spears and darts; that it was regarded by the whole army as a more formidable enemy than even Carthage itself; and that the whole adjacent region being tainted with the pestilential effluvia proceeding from its remains, and the waters with its blood, the Roman army was obliged to remove its station. The skin of the monster was 120 feet long, and was sent to Rome as a trophy."

Another account says, that "it caused so much trouble to Regulus, that he found it necessary to contest the possession of the river with it, by employing the whole force of the army, during which a considerable number of soldiers were lost, while the serpent could neither be vanquished nor wounded; the strong armour of its scales easily repelling the force of all the weapons that were directed against it: upon which recourse was had to battering engines, with which the animal was attacked in the manner of a fortified tower, and was thus at length overpowered. Several discharges were made against it without success, till its back being broken by an immense stone, the monster began to lose its powers, and was with difficulty destroyed, after having diffused such a horror among the army, that they confessed they would rather attack Carthage itself, than such another monster."

The flesh of the serpent is eaten by the Indians and Negroes of Africa, and they make its skin into garments.

The following account of THE AMERICAN SEA SERPENT, is given in the words of an eye-witness:--"I, the undersigned Joseph Woodward, captain of the Adamant schooner, of Hingham, being on my rout from Pen.o.bscot to Hingham, steering W. N. W., and being about ten leagues from the coast, perceived, last Sunday, at two P. M. something on the surface of the water, which seemed to me to be of the size of a large boat. Supposing that it might be part of the wreck of a ship, I approached; but when I was within a few fathoms of it, it appeared, to my great surprise, and that of my whole crew, that it was a monstrous serpent. When I approached nearer, it coiled itself up, instantly uncoiling itself again, and withdrew with extreme rapidity. On my approaching again, it coiled itself up a second time, and placed itself at the distance of sixty feet at most, from the bow of the ship.

"I had one of my guns loaded with a cannon ball and musket bullets. I fired it at the head of the monster; my crew and myself distinctly heard the ball and bullets strike against the body, from which they rebounded, as if they had struck against a rock. The serpent shook his head and tail in an extraordinary manner, and advanced toward the ship with open jaws. I had caused the cannon to be reloaded, and pointed it at his throat; but he had come so near, that all the crew were seized with terror, and we thought only of getting out of his way. He almost touched the vessel, and had not I tacked as I did, he would certainly have come on board. He dived; but in a moment we saw him appear again, with his head on one side of the vessel, and his tail on the other, as if he was going to lift us up and upset us. However, we did not feel any shock. He remained five hours near us, only going backward and forward.

"The fears with which he at first inspired us having subsided, we were able to examine him attentively. I estimate, that his length is at least twice that of my schooner, that is to say, 130 feet; his head is full twelve or fourteen; the diameter of the body below the neck, is not less than six feet; the size of the head is in proportion to that of the body.

He is of a blackish colour, his ear-holes, (ornes,) are about twelve feet from the extremity of his head. In short, the whole has a terrible look.

When he coils himself up, he places his tail in such a manner, that it aids him in darting forward with great force: he moves in all directions with the greatest facility and astonishing rapidity.

(Signed,) "Joseph Woodward."

"_Hingham_, May 12, 1818."

This declaration is attested by Peter Holmes and John Mayo, who made affidavit of the truth of it before a justice of peace.

On the FASCINATING POWER OF SERPENTS.--Major Alexander Garden, of South Carolina, has, in a paper read to the New York Historical Society, attributed the supposed power of fascination possessed by serpents, to a vapour which they can spread around them, and to objects at a little distance, at pleasure. He first reduces the exaggerated idea which has been entertained of this power, and then adduces instances of the effect of a sickening and stupifying vapour, perceived to issue from the animal.

A negro is mentioned, who, from a very peculiar acuteness in smell, could discover the rattlesnake at a distance of two hundred feet, when in the exercise of this power; and on following this indication, always found some animal suffering from its influence.

We shall now give some curiosities respecting Worms; and first, of THE CATERPILLAR.--The larvae of b.u.t.terflies are universally known by the name of caterpillars, and are extremely various in their forms and colours, some being smooth, others beset with either simple or ramified spines, and some are observed to protrude from their front, when disturbed, a pair of short tentacula, or feelers, somewhat a.n.a.logous to those of a snail. A caterpillar, when grown to its full size, retires to some convenient spot, and, securing itself properly by a small quant.i.ty of silken filaments, either suspends itself by the tail, hanging with its head downwards, or else in an upright position, with the body fastened round the middle by a number of filaments. It then casts off the caterpillar-skin, and commences chrysalis, in which state it continues till the b.u.t.terfly is ready for birth, which, liberating itself from the skin of the chrysalis, remains till its wings, which are at first short, weak, and covered with moisture, are fully extended; this happens in about a quarter of an hour, when the animal suddenly quits the state of inactivity to which it had been so long confined, and becomes at pleasure an inhabitant of the air.

It will now be proper to give some account of THE CATERPILLAR-EATERS.--Caterpillar-eaters are a species of worms bred in the body of the caterpillar, and which eat its flesh. These are produced by a certain kind of fly, that lodges her eggs in the body of this insect; and they, after their proper changes, become flies like their parents. Mr.

Reaumur has given us, in his History of Insects, some very curious particulars respecting these little worms. Each of them spins itself a very beautiful case, of a cylindric figure, of a very strong sort of silk, in which this animal spends its state of chrysalis; and they have a mark by which they may be known from all other animal productions of this kind, which is, that they have always a broad stripe or band surrounding their middle, which is black when the rest of the case is white, and white when that is black. Mr. Reaumur has had the patience to find out the reason of this singularity. The whole sh.e.l.l is spun of a silk produced out of the creature's body; this at first runs all white, and towards the end of the spinning turns black. The outside of the case must necessarily be formed first, as the creature works from within; consequently this is truly white all over, but it is transparent, and shews the last spun, or black silk, through it. It might be supposed that the whole inside of the sh.e.l.l should be black; but this is not the case: the whole is fashioned before this black silk comes; and this is employed by the creature, not to line the whole, but to fortify certain parts only; and therefore is all applied either to the middle,--or to the two ends, omitting the middle,--or a blackness at both ends, leaving the white in the middle to appear. It is not uncommon to find a sort of small cases, in garden walks, which appear to move of themselves; when these are opened, they are found to contain a small living worm. This is one of the species of these caterpillar-eaters; which, as soon as it comes out of the body of that animal, spins itself a case for its transformation, and lives in it without food till that change comes on, when it becomes a fly, like that to which it owed its birth.

In the next place we shall introduce a subject of great curiosity, well known by the name of THE SILK-WORM.--The silk-worm is a species of caterpillar, and, like it, is formed of several moveable rings, and is well furnished with feet and claws, to rest and fix itself where it pleases. It has two rows of teeth, which do not move upwards and downwards, but from right to left, which enables it to press, cut, and tear the leaves in every direction. Along the whole length of its back we perceive through its skin a vessel which performs the functions of a heart. On each side of this insect are nine orifices, which answer to as many lungs, and a.s.sist the circulation of the chyle, or nutritive juice.

Under the mouth it has a kind of reel with two holes, through which pa.s.s two drops of the gum with which its bag is filled; they act like two distaffs, continually furnishing it with the materials of which it makes its silk. The gum which distils through the two holes takes their form, lengthens into a double thread, which suddenly loses the fluidity of the liquid gum, and acquires the consistence necessary to support or to envelope the worm. When that time arrives, it joins the two threads together, by gluing them one over the other with its fore feet. This double thread is not only very fine, but also very strong, and of great length. Each bag has a thread which is nearly five hundred ells long; and as this thread is double, and joined together throughout its length, each bag will be found to contain a thousand ells of silk, though the whole weight does not exceed two grains and a half.

The life of this insect in its vermiform state is very short, and it pa.s.ses through different states till it gradually arrives at its greatest degree of perfection. When it first emerges from the egg, it is extremely small, perfectly black, and its head of a still brighter black than the rest of its body: in a few days it begins to grow white, or of an ash colour; its coat becomes dirty and ruffled; it casts it off, and appears in a new dress; it becomes larger and much whiter, though a little tinged with green, from feeding upon green leaves. After a few more days (the length of time varying according to the degree of heat and quality of its nourishment) it ceases to eat, and sleeps for about two days; it then agitates and frets itself extremely, becoming red with the efforts it makes; its skin wrinkles and shrivels up, and it throws it off a second time, together with its feet. Within the s.p.a.ce of three weeks or a month, we see it fresh dressed three times. It now begins to eat again, and might be taken for a different creature, so much is the appearance of its head, colour, and figure, altered. After continuing to eat for some days, it falls again into a lethargic state; on recovering from which, it once more changes its coat, which makes the third since it issued from its sh.e.l.l. It continues to eat for some time, then, entirely ceasing to take any nutriment, prepares for itself a retreat, and draws out a silken thread, which it wraps round its body in the same manner as we might wind thread round an oval piece of wood. It remains quietly in the bag it has formed, and at the end of fifteen days would pierce it, to issue forth, if it was not killed by being exposed to the heat of the sun, or shut up in an oven.

The silk-bags are thrown into hot water, and stirred about with birch twigs to draw out the heads or beginning of the threads, and the silk is afterwards wound upon reels made for the purpose. Thus we are indebted to this little insect for our greatest luxury in clothing: a reflection which ought to humble our pride; for how can we be vain of the silk which covers us, when we reflect to what we are indebted for it, and how little we are instrumental in the formation of those beauties in our clothing, of which we are vain? Thus we find the most insignificant and despicable objects are the instruments of ornament and advantage to man; an insect that we scarcely condescended to look at, becomes a blessing to thousands of human beings, forms an important article of trade, and is the source of great riches.

Our next subject is, THE TAPE-WORM.--This genus of worms is destined to feed on the juices of various animals, and they inhabit the internal parts of almost every species of living beings. The structure and physiology of the taenia are curious, and it may be amusing as well as instructive to consider it with attention. The taenia appears destined to feed upon such juices of animals as are already animalized; and it is therefore most commonly found in the alimentary ca.n.a.l, and in the upper part, where there is the greatest abundance of chyle, for chyle seems to be the natural food of the taenia. As it is thus supported by food which is already digested, it is dest.i.tute of the complicated organs of digestion. As the taenia solium is most frequent in this country, it may be proper to describe it more particularly.

It is from three to thirty feet long; some say sixty feet. It is composed of a head, in which are a mouth adapted to drink up fluids, and an apparatus for giving the head a fixed situation. The body is composed of a great number of distinct pieces articulated together, each joint having an organ by which it attaches itself to the neighbouring part of the inner court of the intestine. The joints nearest the head are always small, and they become gradually enlarged as they are farther removed from it; but towards the tail a few of the last joints again become diminished in size.

The extremity of the body is terminated by a small semicircular joint, which has no opening in it.

The head of this animal is composed of the same kind of materials as the other parts of its body; it has a rounded opening at its extremity, which is considered to be its mouth. This opening is continued by a short duct into two ca.n.a.ls; these ca.n.a.ls pa.s.s round every joint of the animal's body, and convey the aliment. Surrounding the opening of the mouth, are placed a number of projecting radii, which are of a fibrous texture, and whose direction is longitudinal. These radii appear to serve the purpose of tentacula, for fixing the orifice of the mouth, from their being inserted along the brim of that opening. After the rounded extremity or head has been narrowed into the neck, the lower part becomes flatted, and has two small tubercles placed on each flatted side; the tubercles are concave in the middle, and appear destined to serve the purpose of suckers, for attaching the head more effectually. The internal structure of the joints composing the body of this animal is partly vascular and partly cellular; the substance itself is white, and somewhat resembles in its texture the coagulated lymph of the human blood. The alimentary ca.n.a.l pa.s.ses along each side of the animal, sending a cross ca.n.a.l over the bottom of each joint, which connects the two lateral ca.n.a.ls together.

Mr. Carlisle injected, with a coloured size, at a single push with a small syringe, three feet in length of these ca.n.a.ls, in the direction from the mouth downwards. He tried the injection the contrary way, but it seemed to be stopped with valves. The alimentary ca.n.a.l is impervious at the extreme joint, where it terminates without any opening a.n.a.logous to an a.n.u.s. Each joint has a vascular joint occupying the middle part, which is composed of a longitudinal ca.n.a.l, from which a great number of lateral ca.n.a.ls branch off at right angles. These ca.n.a.ls contain a fluid like milk.

The taenia seems to be one of the simplest vascular animals in nature. The way in which it is nourished is singular; the food being taken in by the mouth, pa.s.ses into the alimentary ca.n.a.l, and is thus made to visit in a general way the different parts of the animal. As it has no excretory ducts, it would appear that the whole of its alimentary fluid is fit for nourishment; the decayed parts probably dissolve into a fluid, which transudes through the skin, which is extremely porous.

This animal has nothing resembling a brain or nerves, and seems to have no organs of sense, but those of touch. It is most probably propagated by ova, which may easily pa.s.s along the circulating vessels of other animals.

We cannot otherwise explain the phenomena of worms being found in the eggs of fowls, and in the intestines of a foetus before birth, except by supposing their ova to have pa.s.sed through the circulating vessels of the mother, and by this means to have been conveyed to the foetus.

The chance of an ovum being placed in a situation where it will be hatched, and the young find convenient subsistence, must be very small; hence the necessity for their being very prolific. If they had the same powers of fecundity which they now possess, and their ova were afterwards very readily hatched, then the multiplication of these animals would be immense, and become a nuisance to the other parts of the creation.

Another mode of increase allowed to taenia, (if we may call it increase,) is by an addition to the number of their joints. If we consider the individual joints as distinct beings, it is so; and when we reflect upon the power of individuality given to each joint, it makes this conjecture the more probable. We can hardly suppose that an ovum of a taenia, which at its full growth is thirty feet long, and composed of four hundred joints, contained a young taenia composed of this number of pieces; but we have seen young taenia not half a foot long, and not possessed of fifty joints, which still were entire worms. We have also many reasons to believe, that when a part of this animal is broken off from the rest, it is capable of forming a head for itself, and of becoming an independent being. The simple construction of the head makes its regeneration a much more easy operation than that of the tails and feet of lizards, which are composed of bones and complicated vessels; but this last operation has been proved by the experiments of Spallanzani, and many other naturalists.

An article of great curiosity is, THE SHIP-WORM.--This worm has a very slender, smooth, cylindrical sh.e.l.l; it inhabits the Indian seas, whence it was imported into Europe. It penetrates easily into the stoutest oak planks, and produces dreadful destruction to the ships, by the holes it makes in their sides: and it is to avoid the effects of this insect that vessels require sheathing.

The head of this creature is coated with a strong armour, and furnished with a mouth like that of the leech. A little above this it has two horns, which seem a kind of continuation of the sh.e.l.l; the neck is furnished with several strong muscles; the rest of the body is only covered by a very thin transparent skin, through which the motion of the intestines is plainly seen by the naked eye. This creature is wonderfully minute when newly excluded from the egg, but it grows to the length of four or six inches, and sometimes more. When the bottom of a vessel, or any piece of wood which is constantly under water, is inhabited by these worms, it is full of small holes; but no damage appears till the outer parts are cut away. Then their sh.e.l.ly habitations come into view, in which there is a large s.p.a.ce for inclosing the animal, and surrounding it with water. There is an evident care in these creatures never to injure each other's habitations; by which means each case or sh.e.l.l is preserved entire. These worms will appear, on a very little consideration, to be most important beings in the great chain of creation, and pleasing demonstrations of the infinitely wise and gracious Power, which formed, and still preserves the whole, in such wonderful order and beauty; for if it were not for the rapacity of these and such animals, tropical rivers, and indeed the ocean itself, would be choked with the bodies of trees which are annually carried down by the rapid torrents, as many of them would last for ages, and probably be productive of evils, of which, happily, we cannot in the present state of things form any idea; whereas, being consumed by these animals, they are more easily broken in pieces by the waves; and the fragments which are not devoured become specifically lighter, and are consequently more readily and more effectually thrown on sh.o.r.e, where the sun, wind, insects, and various other instruments, speedily promote their entire dissolution.