THE MESENTERY. 51 



intestine is in the pelvis ; but when those viscera are filled, the 

 intestine is in the general cavity of the abdomen. 



The Mesentery 



Is a process of the peritoneum, which is formed in the manner 

 of a plait or fold, and of course consists of two lamina. These 

 lamina proceed from the back part of the abdomen, and are 

 so near to each other, that they compose one substantial 

 process ; having cellular and adipose substance, blood-vessels 

 and nerves, with absorbent or lacteal vessels and their glands 

 between them. 



The form of this process, when it is separated from the back, 

 and the intestines are detached from it, is somewhat semicircu- 

 lar ; that portion of its margin or edge which corresponds to 

 the diameter of the semicircle, is connected to the back of the 

 abdomen, and called the root of the mesentery ; the edge, 

 which is the circumference of the semicircle, is connected with 

 the intestine. The edge connected with the back of the abdo- 

 men is commonly about five or six inches in length : the semi- 

 circular edge, instead of extendino- fifteen or eighteen inches, 

 the ordinary proportion, is attached to a portion of intestine 

 sometimes twenty-four feet in length. The mesentery, on 

 account of this great difference between its diameter and cir- 

 cumference, has been compared to the ruffle of a shirt sleeve; 

 its roots being taken for the plaited edge of the ruffle, and the 

 circumference for its loose edge. But the comparison is not 

 precisely accurate ; for the mesentery is not plaited at its root, 

 but perfectly smooth, and free from every kind of fold. It 

 begins to enlarge towards its circumference, and enlarges to 

 that degree that it falls into plaits or folds : precisely such as 

 would exist in a semicircular piece of membrane about six 

 inches in diameter, if a number of simple incisions, of about an 

 inch and a half in length, were made in a radiated direction 

 from the circumference, and if portions like a sextant or quad- 

 rant were taken from a circular membrane three inches in 

 diameter, and united by their edges to these incisions, so that 

 their circumference might be continuous with the circumference 



