ENTERITIS. 487 



areolar tissue which binds together the small glandular epithelium 

 cells,) so that the return of blood from the cajDillaries meets with a 

 certain degree of resistance. A similar effect is produced, also by 

 another anatomical peculiarity of the intestinal circulation, viz., that 

 while the arteries in their passage through the muscularis * of the 

 intestine are surrounded by quite a strong sheath of connective tis- 

 sue, the venous twigs, on the contrary, pierce the muscular coat in 

 an exposed condition, so that every muscular contraction produces 

 more or less interference with the return flow of blood. Finally, 

 from the fact that during the process of digestion the chyle t-ves- 

 sels of the mesenterj^ always contain red blood-corpuscles, it may 

 probably be inferred that the intestinal mucous membrane is one 

 of the regions of the body where the passage of blood cells through 

 the walls of the vessels takes place with special facility. It is not 

 surprising, therefore, that the intestitial mucous membrane should 

 be particularly liable to inflammation, and that even slight irrita- 

 tions may suffice to excite the same. 



The exciting causes of enteritis are therefore extremely numer- 

 ous, as the following enumeration will abundantly show. 



Not to speak of the inflammations which are produced by the 

 extension to the intestinal mucous membrane of an inflammation 

 in a neighboring organ, the occurrence of such always presupposes 

 one of two causes : either the irritations are of abnormal character, 

 the mucous membrane being normal, or for some cause, the 

 intesti7ial mucous inembrane has lost its 7tormal character, so 

 that even normal irritations are sufficient to excite an inflam- 

 mation. 



Under the first of these classes of causes are included all articles 

 of food which produce severe mechanical or chemical irritation, as 

 indigestible or fermenting food, foreig7i bodies, poisons and power- 

 ful purgative medicines. Intestinal inflammation is sometimes 

 produced also by a massive accumulation of worms. Another not 

 unfrequent cause is the presence of intestinal concretions, or in- 

 durated faeces, especially above places where the intestine has been 

 narrowed by a bend of the bowels, adhesions, etc. The latter of 

 these causes — faecal impaction — not merely acts mechanically upon 



* Muscularis. Belonging to the muscles, 



t Chyle. The milk-like substance from which blood is formed. 



