dlated, for the first time in modern days, by that excellent veterinary surgeon Mr. Bracy Clark, in the "Transactions of the Linnean Society," vol. 3.

These animals, which are called botts, attach themselves to every part of the stomach, but are in general most numerous about the pylorus; and are sometimes, but much less frequently, found in the intestines. They hang most commonly in clusters, being fixed by the small end to the inner membrane of the

stomach, where they adhere by means of two small hooks or tentacula. When removed from the stomach, they will attach themselves to any loose membrane, and even to the skin of the hand: for this purpose they draw back their hooks almost entirely within the skin, till the two points of these hooks close to each other; they then present them to the membrane, and keeping them parallel till it is pierced through, they expand them in a lateral direction; and afterwards, by bringing the points downwards, or towards themselves, they include a suffi cient piece of the membrane with each hook, and thus remain firmly fixed, for any length of time, without any further exertion of the animal. They attain their full growth about the latter end of May, and are coming from the horse from this time to the latter end of June. On drop

ping to the ground, they soon change to the crysalis, and in six or seven weeks the fly appears. This bott is larger and whiter than that of the estrus hæmorrhoidalis, which has a reddish cast; but in its structure, and situation in the animal, resembles the former. It is found, however, to hang about the rectum, previously to quitting it, which the large horse-bott never does.

Veterinary practitioners do not seem to have decided, hitherto, whether these animals are prejudicial to the horse; nor even whether they may not be actually beneficial. Their almost universal exist ence at a certain season, even in animals perfectly healthy, shows that they produce no marked ill effect; yet the holes which they leave, where they were attached to the stomach, could hardly be made without causing some injurious irri

tation.

The food of carnivorous animals approaching in its constituent elements more nearly to those of the animal than that of the herbivorous tribes, is more

easily reduced into the state which is required for the nourishment of the body

in the former than in the latter case. Hence arises a leading distinction between the stomachs of these classes. In the latter animals, the œsophagus opens considerably to the right of the great extremity, so as to leave a large cul de sac on the left side of the stomach; and the small intestine commences near the cardia, leaving a similar blind bag on the right. The food must be detained for a long time in such a stomach, as the passage from the esophagus to the pylorus is indirect, and highly unfavourable to speedy transmission. Animals of the mouse kind, and the rodentia, show this structure very well; it is very remarkable in the mus quercinus, (Cuvier, "Leçons," &c. tom. 5. pl. 36. fig. 11.) In the carnivora, the stomach, which is of a cylindrical form, has no cul de sacs; the œsophagus opens at its anterior extremity, and the intestine commences from the posterior; so that every thing favours a quick passage of the food. Animals of the weasel kind, which are very truly carnivorous, exhibit this structure the most completely. The seal also exemplifies it, and the lion. (Cuvier, pl. 36. fig. 7.)

The most complicated and artificial arrangement, both with respect to struc ture and mechanism, is found in the well-known four stomachs of the rumi. nating animals with divided hoofs: of this we shall take, as examples, the cow and sheep.

The first stomach or paunch, (rumen, penula, magnus ventor, ingluvies, is by far the largest in the adult animal; not so however in the recently born calf or lamb. It is divided externally into two saccular appendices at its extremity, and it is slightly separated into four parts on the inside. Its internal coat is beset with innumerable flattened papillæ.

This is followed by the second stomach, honeycomb bag, bonnet, or king's hood, (reticulum, ollula,) which may be regarded as a globular appendage of the paunch; but it is distinguished from the latter part by the elegant arrange. ment of its internal coat, which forms polygonal and acute-angled cells, or superficial cavities.

The third stomach, which is the smallest, is called the manyplus, which is a

corruption of manyplies (echinus, con. clave, centipellio, omasum): it is distinguished from the two former, both by its form, which has been compared to that of a hedge-hog when rolled up, and by its internal structure. Its cavity is much contracted by numerous and broad du plicatures of the internal coat, which lie lengthwise, vary in breadth in a regular alternate order, and amount to about 40 in the sheep, and 100 in the cow.

The fourth, or the red, (abomasum, faliscus, ventriculus intestinalis) is next in size to the paunch, of an elongated, pyri. form shape, with an internal villous coat like that of the human stomach, with large longitudinal rugæ.

The three first stomachs are connected with each other, and with a groove-like continuation of the esophagus, in a very remarkable way. The latter tube enters just where the paunch, the second and third stomachs, approach each other; it is then continued with the groove, which ends in the third stomach. This groove is therefore open to the first stomachs, which lie to its right and left. But the thick prominent lips which form the mar gia of the groove admit of being drawn together so as to form a complete canal; which then constitutes a direct continua. tion of the esophagus into the third stomach.

The functions of this very singular part will vary, according as we consider it in the state of a groove, or of a closed canal. In the first case, the grass, &c. is passed, after a very slight degree of mastication, into the paunch, as into a reservoir. Thence it goes in small portions into the second stomach, from which, after a further maceration, it is propelled, by a kind of antiperistaltic motion, into the oesophagus, and thus returns into the mouth. It is here ruminated, and again swallowed, when the groove is shut, and the morsel of food, after this second mastication, is thereby conducted directly into the third stomach. During the short time which it probably stays in this situation between the folds of the internal coat, it is still further prepared for digestion, which process is completed in the fourth or true digestive stomach.

The phenomena of rumination suppose a power of voluntary motion in the part. And indeed the influence of the will in the whole function is incontestible. It is not confined to any particular time, since the animal can delay it according to circumstances, when the paunch is quite

full. It has been expressly stated of some men, who have had the power of raminat. ing, (instances of which are not very rare) that it was quite voluntary with them. Blumenbach knew two men, who rumi nated their vegetable food: both assured him that they had a real enjoyment in doing this, which has also been observed of others; and one of them had the power of doing it, or leaving it alone, according to circumstances.

The final purpose of rumination, as applicable to all the animals in which it takes place, and the chief utility of this wonderfully complicated function in the animal economy, are still completely unknown. What has been already suggest ed on these points is completely unsatisfactory. The old dream of Aristotle and Galen, that rumination supplies the place of incisor teeth, the materials of which are applied, in these animals, to the formation of horns, scarcely deserves mention. Perault and others supposed, that it contributed to the security of these animals, which generally eat much and are timid, by showing the necessity of their remaining long employed in chew ing in an open pasture. But the Indian buffalo ruminates, although it does not fly even from a lion, but rather attacks, and often vanquishes that animal: and the wild goat dwells in Alpine countries, which are inaccessible to beasts of prey.

The peculiar structure of the stomach in the camel and lama, which enables these animals to take at one time a suffi cient quantity of water to last them for two, three, or more days, and thereby renders them adapted to inhabit the dry and sandy deserts, which constitute their natural abode, is highly worthy of atten tion. The fluid which they drink is depo sited in numerous cells, formed in the substance of their first and second stomachs, by strong bands of muscular fi bres crossing each other at right angles. It should seem that the animal has the power of closing these cells by the contraction of those fibres which form the mouths of the cavities, or of expelling the contained fluid by putting the other portions of fibres in action.

This cellular structure is found in two parts of the first stomach; and it occu pies the whole of the second. It was found in a dead camel, that these cavities would hold two gallons of fluid; but they were probably more capacious during life, as the animal in question always drank six or seven gallons of water every

other day, and took more in the intermediate time. Mr. Bruce states, in his travels, that he procured four gallons from one which he slaughtered in Upper Egypt. "Shaw's Abridgment of Bruce's Travels." Ed. 3. p. 371.

As all the food which the animal takes passes into the first stomach, the water of the cells in that part becomes turbid; but it remains perfectly pure in the second, where it resides in the greatest quantity; which circumstance accounts for travellers being able to drink it on an emergency. The muscular bands, which form the groove described in the account of the ruminating stomach, are particularly strong; and by drawing the third stomach to the esophagus, convey the ruminated food through the second, without polluting the water in its cells. Hence the food that has been macerated in the paunch must be sent back to the mouth directly from that cavity, without passing into the second stomach, as it does in the cow. See "Observations on the camel's stomach respecting the water which it contains," &c. by E. Home, esq. Philos. Trans 1806.

The structure of these parts in the lama, according to the account which Cuvier has given of them, from the examination of a fetus, does not seem to differ essentially from that of the camel.

There is a peculiar glandular body at the upper orifice of the beaver's stomach, about the size of a florin, full of cavities that secrete mucus. It resembles, on the whole, the bulbus glandulosus of birds, and assists in the digestion and animalization of the dry food which this curious animal takes, consisting chiefly of the bark and chips of

trees, &c.

.

According to Cuvier, there is a gland as large as the head of a man, situated between the coats of the stomach in the manati (trichechus manatus borealis). It is placed near the oesophagus, and discharges, on pressure, a fluid like that of the pancreas, by numerous small openings.

Mr. Home is of opinion that the glandular structure exists in the stomach of the sea-otter near the pylorus. Philos. Trans. 1796. pl. 2. And Mr. Macartney has discovered an arrangement of glandular bodies in the dormouse, round the esophagus, just before its termination, similar in situation and appearance to the gastric glands of birds."

The stomach of the pangolin (manis pentadactyla) is almost as thick and mus

(ESOPHAGUS AND STOMACH OF BIRDS.

The œsophagus is of immense size in many carnivorous birds; considerably larger indeed than the intestinal canal. The capaciousness of this tube enables it to hold for a time the entire fish and large bones which these birds swallow, and which cannot be contained in the stomach; and to facilitate the discharge, by vomiting the indigestible remains of the food, which form balls of hair, feathers, and bony matter.

the sternum into the crop, (ingluvies, The œsophagus expands just before prolobus, le jabot,) which is furnished with numerous mucous or salivary glands, disposed in many cases in regular rows. In such birds as nourish their young from the crop the glands swell remarkably at that time, and secrete a greater quantity of fluid. This part is found in landbirds only, but not in all of these; it exists in all the galline, and in some birds of

prey.

There is another glandular and secretory organ, much more common than the crop, belonging, indeed, most probably to the whole class. This is the bulbus glandulosus, (echinus, infundibulum, proventriculus, corpus tubulosum,) which is situated before the entrance of the sophagus into the proper stomach, and whose form and structure vary considerably in the different genera and species. In the ostrich, for example, its magnitude and form give it the appearance a second stomach. In some other birds, as the psittaci, ardex, (crane, stork, &c.) its appearance is different from that of the proper stomach, but its size is larger; while, on the contrary, in gallinaceous

fowls it is much smaller.

This bulbus glandulosus consists of a vast congeries of glands. The œsopha gus, of which it is a dilatation, has a vast number of glandular bodies inter posed between its tunics, and entirely surrounding the tube, so as to constitute the "Zone of gastric glands" of Mr. Macartney. These bodies have a hollow internally, and they open into the cavity of the bulbus by numerous very plain apertures. The fluid secreted by them passes into the gizzard, and mixes with

the food.

A deviation from the natural structure, which is completely unparalleled, occurs in the stomach of the cuckoo. The gizzard of the bird is covered, internally, with an abundance of short, bristle, and spiral hairs, lying close together.

mus

The structure of the stomach differs most widely in the different orders and genera of this class. It appears merely as a thin membranous bag, in several of those which feed on flesh and insects, when compared with the thick cular globes of the granivorous genera. But there are in both many intermediate links between these extremes, and at the same time considerable analogies in the structures, which are apparently the most opposite. This is particularly observeable in the course of the muscu lar fibres, and in the callous structure and appearance of the internal coat; in which points, many of what are called membrahous stomachs have a great resemblance to those of the gallina.

Both parts, but particularly the mus cular, are very strong in the gizzard (ventriculus bulbosus) of granivorous birds. We find here, instead of a muscular coat, four immensely thick and powerful muscles, viz. a large hemispherical pair at the sides (laterales,) and two smaller ones (intermedii) at the two ends of the cavity. All the four are distinguished, by the unparalleled firm ness of their texture, and by the peculiar colour, from all the other muscles of the body.

The internal callous coat must be considered as a true epidermis; since, like that part, it becomes gradually thicker from pressure and rubbing. It forms folds and depressions towards the cavity of the stomach; and these irregularities are adapted to each other on the opposed surface. The cavity of this curious stomach is comparatively small; its lower orifice is placed very near the upper. Every part of the organ is, indeed, calculated for producing very powerful trituration; and this is still further promoted by the well-known instinctive practice of granivorous birds, of swallowing small hard stones with their food.

The end and use of swallowing these stones have been very differently explained. Casalpinus considered it rather as a medicine than as a common assistance to digestion; Boerhaave, as an absorbent for the acid of the stomach; Redi, as a substitute for teeth; according to Whytt, it is a mechanical irritation,

adapted to the callous and insensible na ture of the coats of the stomach; Spallanzani rejected all supposition of design or object, and thought that the stones were swallowed from mere stupidity. There seems not much sagacity to be discover ed in this opinion, when we consider that these stones are so essential to the due digestion of the corn, that birds grow lean without them, although they may be most copiously supplied with food. This paradoxical opinion has, however, been already refuted by J. Hunter and G. Fordyce. Blumenbach thinks that the stones kill the grain, and deprive it of its vitality, which otherwise resists the action of the diges tive powers. Thus it has been found that if the oats and barley given to horses be previously heated, the animal only re quires half the quantity, and thrives equally well.

Reptiles and birds have their nostrils terminated by two longitudinal slits on the palate; they have no velum palati, nor epiglottis.

The esophagus of the serpent kind is of immense magnitude; for these reptiles swallow animals larger than themselves, which are retained for a considerable time in the tube, and descend into the stomach by degrees, where they are slowly subjected to the action of the gas tric juice. The whole process sometimes occupies many days, or even weeks. There is hardly any distinction between esophagus and stomachi.

From the peculiar formation of the nose of fishes, and from their respiring by means of gills, their fauces have no connection with any nasal cavity, or glottis.

The esophagus is of great width in fishes; and is distinguished with difficul ty in many cases from the stomach. These animals swallow their food whole, without subjecting it to any mastication; and if the stomach will not hold the whole, a part remains in the esophagus, until that which has descended lower is digested. The alimentary canal is gene. rally very short; sometimes extending straight from the mouth to the anus with very little dilatation, as in the lamprey (petromyzon marinus.)

The crustacea, and some insects, are furnished with organs of mastication of similar structure. Their mouth is formed of two or more pairs of jaws placed laterally. These move from without in wards, and vice versa; whereas those of red-blooded animals move from above downwards, and back again. The parts

which are termed the lips of insects are two bodies, of which one is placed above or in front of the jaws, and the other below or behind them. The palpi or feelers are articulated to the jaws. All insects which have jaws, possess the power of masticating hard animal and vegetable substances; for these parts are of a firm horny texture, and in many cases are very large, when compared with the size of the animal.

The locust (grylli,) the dragon-fly (libellula,) the beetles, and particularly the lucanus cervus, or stag-beetle, and the staphylinus maxillosus, are examples in which the jaws are very large and manifest, and often possess denticulated edges. All the genera of the following order have jaws; viz. the coleoptera, orthoptera, neuroptera, and hymenopteга. The insects of the remaining orders derive their nourishment chiefly from liquids; which they get either from animal or vegetable substances by means of a spiral and tubular tongue, or soft proboscis, as in the lepidoptera; with a broad opening, admitting of extension and retraction (the hemiptera ;) or a horny pointed tube, containing sharp bristly bodies internally (the diptera and aptera.)

The stomach of the bee is a transparent membranous bag, in which the nectar of the flowers is elaborated and converted into honey. The animal vomits it up from this reservoir, and deposits it in the hive.

The stomach of the crab and lobster is a very singular organ. It is formed on a bony apparatus, in short, a species of skeleton, and does not therefore collapse when empty. To certain parts of this bony structure, round the pylorus, the teeth are affixed. Their substance is extremely hard, and their margin is serrated or denticulated; as they surround the tube, near the pylorus, nothing can pass that opening without being perfectly comminuted. These bones and teeth are moved by peculiar muscles.

In those mollusca, which possess jaws, these parts are fixed in the flesh of the animal, as there is no head to which they can be articulated. They are two in number in the cuttle-fish, are composed of a horny substance, and resemble exactly the bill of a parrot. They are placed in the centre of the lower part of the body, and are surrounded by the tentacula, which enable the animal to attach itself to any object. By means of these parts, the sbell-fish, which are taken for food, are completely triturated. The common snail

and slug have a single jaw, semilunar in its form, and denticulated. The tritonia has two jaws, which act like the blades of a pair of scissars. The other mollusca possess no organs of this kind, but have, in some instances, a sort of proboscis ; as the buccinum, murex, voluta, doris, scyllæa, &c.

In the worms, properly so called, there are sometimes hard parts, forming a kind of jaws or teeth; thus in the nereis, the mouth possesses several calcareous pieces. The ophrodite (sea-mouse) has a proboscis, furnished with four teeth, which it can extend and retract at pleasure. Within the mouth of the leech are three semicircular projecting bodies, with a sharp denticulated edge: by this apparatus the animal inflicts its wound of the well known peculiar form in the skin.

The teeth of the echinus (sea-hedgehog) are of a very singular arrangement; a round opening is left in the shell for the entrance of the food; a bony structure, on which five teeth are placed, fills up this aperture; and as these parts are moved by numerous muscles, they form a very complete organ of mastication.

The stomach of the vermes is, in general, a membranous bag, but in some cases its structure is more complicated. The helix stagnalis and the onchidia have gizzards. The aplysia has three strong muscular stomachs, provided with pyramidal bony processes. The latter structures, together with those of the lobster and crab, present a new analogy, as Cuvier has observed, between the membranes of the intestines and the integu ments of the body. This is particularly strengthened by the annual shedding of the lobster's teeth, when its crustaceous covering falls off.

The bulla lignaria has a very powerful stomach, containing three hard calcareous shells, by which the animal is enabled to bruise and masticate the other testacca on which it feeds.

ON THE INTESTINAL CANAL.

The intestinal canal (which is the most common part in the whole animal kingdom after the stomach) is distinguished in the mammalia by two peculiarities, which depend on the mode of nutrition. It is comparatively shorter in carnivorous animals, and there is also in these less dif ference, to external appearance, between the small and the large intestine than in the herbivora. Yet these rules are not without their exceptions; for the seal has