THE STOMACH. 385 



The general disposition of the peritoneum varies but little in the different species, the 

 only notable diversities being remarked in the great omentum. In the Ox, Sheep, and 

 Goat, this is detached from the middle of the lower face of the rumen, and envelops the 

 right sac of that organ, fixing the fourth compartment to its great curvature, and then 

 passing upwards to become continuous with the mesentery. In the Dog and Pig, this 

 fold descends in front of the intestinal mass until near the pelvis : then it ascends in 

 gathering on itself, and ultimately spreads over the colon : in the middle portion of the 

 great omentum there are, consequently, four layers placed against each other. 



COMPARISON OF THE ABDOMINAL CAVITY OF MAN WITH THAT OF ANIMALS. 



The abdominal cavity of Man is elongated vertically, and has an inferior cavity 

 occupying the entrance to the pelvis. There is nothing particular to note in its disposi- 

 tion, the differences observed in it being allied to the external shape of the body. Tho 

 peritoneum is spread over its parietes nearly in the same manner as in the Carnivora ; 

 the great omentum is constituted by four layers, and covers the intestines like an apron : 

 between its two laminje is the lesser cavity of the omentum, virtually in the adult. 



THE STOMACH. 



The stomach is a membranous sac comprised between the ossophagus 

 and intestines, and in which are commenced the essential phenomena of 

 digestion. 



1. The Stomach in Solipeds. (Figs. 182, 183, 184, 185, 186.) 



Preparation. In order to study the relations of this organ, it suffices to open the 

 abdomen and remove the intestinal mass in the following manner : Place the animal in 

 the first position, and very slightly inclined to the left side ; make an incision through 

 the inferior abdominal wall, or, still better, carry it away entirely by a circular incision, 

 taking care not to wound any part of the intestine. The entire viscera should then be 

 withdrawn from the abdominal cavity, and laid on the table which supports the subject ; 

 for this mass cannot be allowed to fall on the ground without risk of being pulled and 

 torn, either in the intestine itself, or those parts which it is desired to preserve intact in 

 the abdomen. Incise the floating colon where it joins the rectum, and the duodenum 

 where it passes behind the great mtsenteric artery ; the base of the caecum should now 

 be detached from the sublumbar surface by the rupture of the cellular tissue which 

 connects it to the right kidney and the pancreas ; the cellular connection between the 

 Litter gland and the terminal extremity of the fourth portion of the large colon should 

 also be broken ; after this, it is only necessary to divide the attachment of the mesenteric 

 bunds to the sublumbar region, with the vessels contained between them. The intestinal 

 mass is then definitively expelled from the abdominal cavity. In this way it is possible to 

 expose, and conveniently prepare, not only the stomach, but also the spleen, liver, pancreas, 

 kidneys, ureters, etc. Nothing more remains than to make known the procedure to be 

 adopted in everting the stomach, in order to study its internal surface, or dissect its deep 

 muscular layer. It is recommended, first, to excise the stomach with at least three inches 

 of the cesopnagus, and eight inches of the duodenum, and cleanse the interior of the organ. 

 This may be done in several ways, but the following is the simplest : a certain quantity 

 of water is introduced into the stomach by fixing the duodenum to a water-tap, the 

 right hand manipulating the organ while the left closes the duodenum to prevent the 

 escape of the liquid. The alimentary substances contained in it are in this way mixed 

 with the water, and may be expelled from the duodenum by pressing the stomach ; this 

 operation being repeated four or five times, thoroughly cleanses the cavity of the organ. 

 To evert the inner surface, it is only necessary to introduce by the duodenum a loop c f 

 wire, and make it pass through the oesophagus ; a strong waxed thread is fastened in 

 the loop and firmly fixed around the oesophagus, when, in pulling back the wire, this 

 extremity is drawn towards the pylorus, and by caroful traction the latter is so dilated 

 as to allow the passage of the cardiac end, and complete eversion of the stomach. Inflation 

 will then give it its normal form and disposition ; with this difference, that the mucoua 

 membrane is external, and the serous tunic internal. 



Lastly, to render the muscular layers of the stomach more evident, it is advisable to 

 plunge the organ into boiling water for some minutes, after which it should be put into 

 cold water. If it is desired to study the external and middle layers, the stomach should 

 be inflated, and its serous covering removed by strips with forceps and the fingers ; if the 

 deep layer is to be examined, the mucous membrane must be removed by means of the 

 forceps and scalpel from a stomach previously everted. 



