THE HUMAN INTESTINAL CANAL. 319 



right side immediately below the diaphragm, and separated 



by the latter from the lungs (Plate Y. Fig. 16, lb). 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 (coecum), 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 Y. Fig. 16, a). Both the large intestine and 



the small intestine are furnished with numerous glands, 



most of them very small, and which secrete 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 



