48 THE JEJUNUM AND ILEUM. 



sometimes appear in the villous coat, or very close to it exte- 

 riorly ; being small flat bodies, with a depression in the centre, 

 and a foramen in the depression. They are sometimes very 

 numerous at the upper extremity of this intestine, and diminish 

 gradually towards the other extremity. 



The biliary and pancreatic ducts open posteriorly into the 

 duodenum, rather above the middle of it. The orifice of these 

 ducts is generally surrounded J)y a small tubercle, which is 

 oblong, somewhat rounded at one extremity, and pointed at 

 the other. Sometimes this orifice is in a plait, like one of the 

 valvula? conniventes. Most commonly the two ducts unite 

 before they perforate the coat, so as to form but one orifice ; 

 and sometimes they open separately, but always very near to 

 each other. 



Absorbent vessels, which contain chyle, are found on the 

 duodenum. 



The Jejunum and lleum 



Are situated in the abdomen very differently from the duode- 

 num. When the cavity is opened and the omenturn raised r 

 they are in full view ; and every portion of them except the 

 two extremities and the parts near them, can readily be moved. 

 This freedom of motion is owing to the manner in which they 

 are invested by the peritoneum ; or, in the technical language 

 of anatomy, to the length of their mesentery. They agree in 

 their structure with the general description of the small intes- 

 tines, but their muscular coat is rather weaker than that of the 

 duodenum. The valvulae conniventes are very numerous and 

 large in the upper part of the tube, or jejunum ; and gradually 

 diminish in number, until they finally disappear in the lower 

 part of the ileum. The villous coat is in perfection in the 

 jejunum, the villi being more conspicuous there than in any 

 other part of the intestinal tube. There are frequently found, 

 exterior to this coat, but intimately connected with it, many 

 small glandular bodies of a roundish form, which are often 

 clustered together at that part of the intestine which corresponds 

 with the interstice of the lamina of the mesentery. They are 



