ZOOTOMY.

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the guts lying in the posterior part of the abdomen, which is thehighest; ami besides, had the omentum reached much fartherdown in us, it would not only have supplied too great a quantityof oil to the lower part of the abdomen, but we should have beenin continual danger of hernia; : and even at present the omentumfrequently passes down with some of the other viscera, and formspart of these tumors. To these, however, the dog is not subject,as his viscera do not press so much on the rings of the abdominalmuscles, and besides are prevented from passing through by a pen-dulous flap of (at. The inferior and anterior lamella of the omen-tum is fixed to the spleen, fundus of the stomach, pylorus, liver,&c. in the same way as the human ; but the superior having noColon to pass over, goes directly to the back-bone. This servesto explain the formation of the small omentum in the humanbody ; which is nothing but the large omentum, having lost itsfat, passing over the stomach and colon, where it reassumes itspinguedo, so proceeds, and is firmly attached to the liver, spine,&c. The striae of fat are pretty regularly disposed through it,accompanying the distribution of the blood-vessels to guard themfrom the pressure of the superincumbent viscera.

This animal’s Stomach, though pretty much resembling the hu-man in its shape, is somewhat differently situated. It lies more longi-tudinal, as indeed all the oilier viscera do, to accommodate them-selves to the shape of the cavity in which they are contained ; thatis, its inferior orifice is much farther down with respect to the supe-rior than the human : by this means the gross food has an easierpassage into the duodenum. Again, the fundus of the humanstomach, when distended, stands almost directly forwards, whichis occasioned by the little omentum tying it so close down tothe back-bone, &c. at its two orifices ; but it not being fixed inthat manner in the dog, the fundus remains always posterior : thisalso answers very well the shape of the different cavities, the dis-tance betwixt the cardia and fundus being greater than that be-twixt the two sides. It seems to be much larger in proportion tothe bulk of the animal than the human, that it might contain agreater quantity of food at once; which was very necessary,since this animal cannot at any time get its sustenance as men do.The turbillion is not so large, nor is there any coarction formingthe antrum Willesii, as in the stomach of man. It is considerablethicker and more muscular than ours, for breaking the cohesionof their food, which they swhllow without sufficient chewing.H ence it is evident the force of the stomach is not so great asSome would have it, nor its contraction so violent : otherwise thatof dogs would be undoubtedly wounded by the sharp bones, &c.they always take down; for the contraction here is still greaterthan in the human stomach, which is much thinner. The rugae oftlie tunica viliosa are neither so large, nor situated transversely, asin the human, but go from one orifice to the other: the reason ofwhich difference is, perhaps, that they might be in less danger ofbeing hurt by the hard substances this creature frequently feedsupon ; and for the same reason there is not the like coarction attheir pylorus.

The intestines of this animal are proportionally much shorterthan onrs ; for the food which these creatures mostly use, soondissolves, and then putrefies; on which account there was no Oc-casion for a long tract of intestines, but on the contrary that itshould be quickly thrown out of the body. The same is to beobserved of all the carnivorous animals. The muscular coat ofthe intestines is also thickqr and stronger than the human, to pro-trude (lie contents quickly and accurately.

The valvula; ennniventts are less numerous, and in a longitudi-nal direction; and the whole tract of the aiiitientaiy canal iscovered with a slime, which lubricates the intestines, saves themfrom the acrimony of the excreinentitious part and facilitates itspassage.

The duodenum differs considerably in its situation from tliehuman. For in mail it first mounts from the pylorus upwards,backwards, and to the right side ; then passes down by the gall-bladder, and, marching over the right kidney and superior part ofthe psoas muscles, makes a curvature upwards; and passes overthe back-bone and vena cava inferior, to the left hypochondriiun,where it gets through the omentum, mesentery, and mesocolon,to commence the jejunum, being firmly tied down all the way,tlie biliary and pancreatic ducts entering at its most dependingpart; whereas, in the dog, the duodenum is fixed at the pylorus

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to tlie concave surface oi the liver, and hangs loose and pendu-lous with the mesentery backwards into the cai ity of tlie abdomen ;then turning up again, is fixed to the back-bone, where it endsin the jejunum ; die bile and pancreatic juice are poured into itat the most depending part. Therefore rhe same intention seemsto have been had in view in tlie formation of this part in both,viz. the giving the chyle, after the liquors of the liver and pan-creas are poured into it, a disadvantageous course, that so itmight be tlie more intimately blended with tlie humours before itsentry into the jejunum, where the lacteals are very numerous:And thus, by reason of their different posture, the same’design(though by a very different order of the parts) is brought aboutin both.

The other small guts are much the same with ours, only shorter.The great guts are also shorter and less capacious than in the hu-man body ; and we take it for a general rule, that all animals thatlive on vegetable food, have not only their small guts considerablylonger, but also their great guts more capacious, than such crea-tures as feed on other animals. Hence man, trom this form ofhis intestines, and that of the teeth, seems to have been originallydesigned for feeding on vegetables cluetiy ; and still the most ofhis food, and all his drink, is of that class.

The appendix vermiformis justly enough deserves tlie name ofan intestinum caecum in this subject, though in the human bodyit does not ; and it has probably been from the largeness ol thispart in this and some other animals, that tlie oldest anatomistscame to reckon that small appendicle in man as one of the greatguts. On its internal surface we observe a great number of mu-cous glands. As all these throw out slime, tlieW principal officewould seem to lie the procuring a sufficient quantity of that mat-ter for the purposes above-mentioned. Still, however, thereseems to be some unknown use tor this organ in other animals;for tlie appendicitis vermiformis in them is either of great sizeor of great length. In a rat, it is rather larger than the stomach’;in others, as swine, and some of tlie animals which live on vege-tables, it has long convolutions, so that the food must be lodgedin it for a long time. Thus probably, some change takes placein the food, which requires a considerable time to effectuate, and,though unknown to us, may answer very useful purposes to theanimal.

The colon has no longitudinal ligaments; anil consequentlyThisgut is not pursed up into different bags or cells as the human ':nor does this intestine make any circular turn round the abdo-men ; hut passes directly across it to the top of tlie os sacrum,where it gets the name ol rectum.

At tlie extremity of the intestinum rectum, or verge of theanus, there are found two bags or pouches, which contain a mostabominable fetid mucus of a yellow colour, for which we knowno use, unless it serves to lubricate the strained extremity of therectum, and defend it against the asperity of tlie fasces, or to sepa-rate some liquor that might otherwise prove hurtful to theirbodies. There is nothing analogous to those sacs in the humansubject, unless we reckon tlie mucilaginous glands tliat are foundmost frequent and largest about the lower part of tlie rectum.

Tlie mesentery is considerably longer than in tlie human body ;that, in his horizontal situation, the intestines may rest securely onthe soft cushion of tlie abdominal muscles. The fat is here dis-posed in tlie same way, and for the sainereason, as in the omentum.Tin- interstices betwixt the fat are filled with a fine membrane. In-stead of a great number of glandular vag® to be found in the hu-man mesentery, we find the glands few in number, and those areclosely connected together; or there is only one large gland to beobserved in the middle of the mesentery of a bog, which from itsimagined resemblance to tlie pancreas and the name of its dis-coverers, is called pancreas Aselht ; but the resemblance, if thereis any, depends chiefly on the connection, the structure being en-tirely different.

The jicwcrais in man lies across the abdomen, tied down by theperilomcimi ; but tlie capacity of this creature’s abdomen not al-lowing of that situation it is disposed more longitudinally, being■ ied to the duodenum, which it accompanies tor someway. Itsduct enters the duodenum about an inch and a half below theductus communis.

The spleen of this animal differs from ours very much, both infigure and situation. It is much more oblong and thin, and lie*

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