THE ALIMENTARY CANAL 181 



Thin as it is it must be thought of as a double sheet 

 between the two surfaces of which run the blood- 

 vessels, nerves, and lymph-channels of the intestine. 

 The tube of the intestine itself should be conceived of 

 as wrapped round by the mesentery. One writer has 

 compared it to the clothesline over which a blanket is 

 hung. Thus the continuation of the mesentery makes 

 the outer or serous coat of the canal. 



At its other border, where the mesentery reaches the 

 dorsal boundary of abdominal cavity its two layers 

 part and spread to be continued as the lining of that 

 cavity, the parietal peritoneum. The shape of the 

 mesentery when entire is difficult to visualize; it must 

 be thought of as following the whole length of the small 

 intestine and much of the large and yet contracted to 

 join the wall of the body along a rather short line of 

 insertion. The resulting structure has been compared 

 with a " ruffle" or " flounce." The stomach has a 

 suspending membrane which is really a mesentery but 

 referred to as the lesser omentum. It comes to the 

 lesser curvature of the stomach from the under side of 

 the liver and is continued over the surface of that large 

 organ to its attachments to the diaphragm and the back 

 of the cavity. 



The serous coat of the stomach leaves the greater 

 curvature of the organ as well as the lesser and the 

 double sheet so formed hangs slack in front of the 

 intestine like a short apron, the great omentum. This 

 is folded at its lower limit and returns to the transverse 

 part of the colon. The great omentum sometimes comes 

 to be a ponderous appendage from the accumulation in 

 it of adipose tissue. 



The Digestive Glands. Associated with the ali- 

 mentary canal are the organs which deliver into its 

 interior the juices required to prepare the food for 

 absorption. These are called glands but the reference 

 is sometimes to bulky organs like the liver and some- 

 times to microscopic features of the lining of the tract. 



