252 ILLINOIS ACADEMY OF SCIENCE 



the inactive juice containing the paramecia. The organisms 

 were observed under the microscope at frequent intervals dur- 

 ing the experiment. After about two hours the animals were 

 observed to move less rapidly than at the beginning of the ex- 

 periment. A little later these slowly moving organisms be- 

 came more transparent and moved more slowly. As digestion 

 proceeded, the transparency of the paramecia increased, and 

 at the end of the third hour the partially digested organisms 

 appeared as shadows. About half an hour later these para- 

 mecia had been completely digested and had gone into solu- 

 tion. These organisms were literally digested while alive and 

 killed by the action of the trypsin itself in the process of 

 digestion. 



The preceding experiment was repeated, and when the ani- 

 mals were partially digested, the bubbling of the hydrogen gas 

 through the liquid was discontinued and the bubbling of oxy- 

 gen gas was substituted. When this was done, the organisms 

 that had not been too much digested were revived, and lived 

 on as normal animals. 



These experiments show that the resistance of these uni- 

 cellular organisms to the digestive action of trypsin is greatly 

 reduced when their oxidative processes are decreased, and that 

 their resistance returns when the oxidative processes are re- 

 stored. The results obtained on these living unicellular or- 

 ganisms would appear to lend support to the hypothesis ad- 

 vanced in explaining the resistance of the living cells of the 

 gastric mucosa to the digestive action of pepsin. 



CONCLUSIONS 



The decreased resistance of a circumscribed area of the 

 stomach to the digestive action of gastric juice is due to a 

 decrease in the oxidative processes of the cells of the area. 

 Gastric ulcer is due to the subsequent digestion of the area by 

 pepsin. 



The resistance of unicellular organisms (paramecia) to the 

 digestive action of the proteolytic enzymes can be increased 

 or decreased by increasing or decreasing the intensity of the 

 oxidative processes of the organisms, the greater the inten- 

 sity of the oxidative processes the greater the resistance, and 

 vice versa. 



