THE ABDOMEN. 227 



tween its folds lie the jejunum and tlie ileum. At first sliort, 

 it gradually increases in length until it gains its maximum, 

 when it again grows short. Between its folds are arteries, 

 veins, lacteals (or lymphatics), and nerves. The arteries are 

 mesenteric hranclies, from thirteen to eighteen in number, 

 which pass from a common centre and radiate, being con- 

 nected, forming arches at the attached border of the small 

 intestine, from which smaller vessels are given off, which 

 pass to break up in supplying the coats of the bowel. The 

 veins, arranged in like manner, terminate in forming the 

 anterior and posterior mesenteric veins, which form the 

 commencement portion of the vena portse. The nerves are 

 some of those branches of the sympathatic which, in radi- 

 ating from the semilunar ganglion, form the solar plexus. 

 The lacteals are lymphatic vessels, which being filled with 

 an opaque milky fluid, chyle, the product of digestion, re- 

 ceive a name distinct from from those in other parts of the 

 body. Passing from the intestinal villi, these minute vessels 

 proceed upwards towards the spine and near the anterior 

 mesenteric artery pass through the mesenteric glands, num- 

 erous greyish nodular bodies, by which the lacteal fluid is 

 rendered cellular and coagulable ; they differ in no point in 

 structure from other lymph-glands of the body. The ter- 

 mination of the lacteals is in the receptaculum chyli, a 

 dilated vessel which receives lymph from the hinder parts 

 of the body and the chyle, and from the anterior part of 

 which the thoracic duct runs forwards and serves to convey 

 the fluid into the venous circulation. This cavity has very 

 thin transparent walls, and is situated between the anterior 

 mesenteric artery and the coeliac axis, in which situation also 

 we may find the semilunar ganglion, the largest ganglion 

 in the body, to which the splanchnic and part of the pneumo- 

 gastric nerves pass, and from which plexus run with the 

 branches of the coeliac axis, anterior and posterior mesen- 

 teric, and renal arteries receiving their names after the ar- 

 teries they surround. Those in the mesentery form the 

 solar plexus. Branches run backwards to the hypogastric 

 plexus. 



The peritoneal coat of the double colon is reflected from 

 the under surface of the loins and covers at once both the 

 diverging and returning portions, so that they are con- 

 tained in a common serous covering terminating in a blind 

 extremity at the sigmoid flexure. That portion between 



