iv DIGESTION IN THE INTESTINE 257 



showed four small perforations in a longitudinal direction, through 

 which the intestinal mucosa was protruding so that it touched the 

 gastric mucous membrane at several points. From this and other 

 concordant results, Contejean concluded that the blood circulation, 

 by carrying away the digestive enzymes, is able to protect the 

 highly vascular organs from their solvent action ; but that this 

 protection is not unlimited, since after a certain time auto-digestion 

 sets in, and is arrested only when the parts exposed to contact with 

 the digestive fluids are once more covered, by regeneration, with a 

 mucous membrane and special epithelium. 



The results obtained under admirable experimental conditions 

 by Contejean revived the question whether living protoplasm can 

 or cannot be attacked by enzymes, and in what the protective 

 action of the epithelia that clothe the mucous membrane consists ? 

 The new fact adduced by Contejean does not solve this problem, 

 because the tissue of the intestinal walls is digested by the gastric 

 juice in which, besides the ferment, the hydrochloric acid must be 

 reckoned with. 



Matthes (1893-94), with the object of clearing up the patho- 

 genesis of gastric ulcers, performed a number of experiments on 

 dogs, and studied with the microscope and the unaided eye the 

 course of cicatrisation after circumscribed or extensive ablations of 

 the gastric mucosa. He found that small losses of tissue were 

 immediately occluded by local muscular contraction, and that 

 ablations of even 6 cm. in diameter fill up promptly to two-thirds 

 their extent, while the exposed part does not increase nor grow 

 deeper by auto-digestion, but heals by a new formation of mucous 

 membrane clothed with epithelium. This was a fact already 

 known to pathologists, who are well a\vare that round ulcers of 

 the stomach may heal up without necessarily leading to perforation 

 by auto-digestion. 



Matthes, by a number of other experiments, arrived at the 

 conclusion that the digestive enzymes are inactive towards living 

 tissues in a healthy state, and are therefore incapable of producing 

 auto -digestion in the body. But the hydrochloric acid of the 

 gastric juice acts as a protoplasmic toxin which first kills the 

 tissue cells, after which they are digested by the pepsin. So that 

 in the experiments of Pavy, Bernard, Lussana and Inzani, 

 Contejean, the phenomenon of the digestion of living tissues is 

 apparent only. They are not digested unless they have been 

 previously killed, or at least profoundly modified by the hydro- 

 chloric acid. Different animal tissues re-act differently to hydro- 

 chloric acid ; some are not altered by it at all ; some very little ; 

 others again are profoundly modified. According to Matthes, 

 this depends on an adaptation of the cells to the external con- 

 ditions under which they live and function. The resistance of 

 the walls of the stomach to the toxic action of the hydrochloric 



VOL. II S 



