THE ALIMENTARY CANAL 61 



mesentery can be seen blood-vessels, lymphatics, and 

 nerves. This suspending sheet thus serves not merely for 

 mechanical support, but also establishes connection be- 

 tween the intestine and the circulatory and nervous sys- 

 tems. The student is apt to find it hard to visualize the 

 mesentery in its actual form ; he is to imagine a membrane 

 which at one edge extends to the entire length of the small 

 intestine and to much of the large, while its other edge is 

 condensed to be inserted into the space of a few inches 

 before the spinal column. What results from these condi- 

 tions has been described as "a ruffle or flounce." Al- 

 though the mesentery is thin it is really a doubled sheet 

 enveloping the intestine. This will be made clear by the 

 diagram, which also shows how the mesentery is continu- 

 ous with the exquisitely smooth, lustrous lining of the ab- 

 dominal cavity, to which is given the name of peritoneum. 

 Dissection of a small animal will give a comprehension of 

 these anatomic facts which can scarcely be gained by 

 reading. 



The stomach has a supporting membrane attached to it 

 along its lesser curvature and uniting it to the liver, which 

 is, in turn, anchored to the dorsal body wall. This mem- 

 brane is, in effect, a mesentery for the stomach, but is called 

 the lesser omentum. An extension of similar tissue hangs 

 from the greater curvature like an apron over the intestinal 

 coils and is called the great omentum. It may become 

 a ponderous appendage from the fat which it sometimes 

 accumulates. The continuation of the mesentery over 

 the external surface of the intestine and the identical 

 covering of the stomach form for these organs what is 

 spoken of as their serous coat. 



The Finer Structure of the Alimentary Organs. We 

 have said that the internal surface of the stomach and of 

 both intestines is provided with glands. The inner layer 

 of the wall of the canal in which these glands occur is 

 called the mucous coat or mucous membrane. This is in 

 reference to the fact that its exposed cells produce the slimy 

 substance, mucus, more familiarly associated with nasal 



