THE HUMAN INTESTINAL CANAL. 319 



right side immediately below the diaphragm, and separated 

 by the latter from the lungs (Plate V. Fig. 16, Z5> The 

 pancreas lies somewhat further back and more to the 

 left (Fig. 16, p). The small intestine is so long that it 

 has to lie in many folds in order to find room in the limited 

 space of the ventral cavity ; these coils are the bowels. 

 They are divided into an upper intestine, called the empty 

 intestine (jejunum}, and a lower, the crooked intestine 

 (ilium). In this latter part lies that part of the small 

 intestine at which, in the embryo, the yelk-sac opens into 

 the intestinal tube. This long, thin intestine then passes 

 into the large intestine, from which it is separated by a 

 peculiar valve. Directly behind this " Bauhinian valve" 

 the first part of the large intestines forms a broad pouch- 

 like expansion, the blind intestine (caecum), the atrophied 

 extremity of which is a well-known rudimentary organ, the 

 vermiform process (processus vermiformis). The large 

 intestine (colon) consists of three parts , an ascending part 

 on the right, a transverse central part, and a descending 

 part on the left. The latter finally curves like an S, called 

 the "sigmoid flexure," into the last part of the intestinal 

 canal, above the rectum, which opens at the back by the 

 anus (Plate V. Fig. 16, a). Both the large intestine and 

 the small intestine are furnished with numerous glands, 

 most of them very small, and which seci'ete mucous and 

 other juices. 



Along the greater part of its length the intestinal canal 

 is attached to the inner dorsal surface of the ventral cavity, 

 or to the lower surface of the vertebral column. It is 

 fastened by means of the thin, membranous plate, called the 

 mesentery, which develops directly under the notochord 

 54 



