350 Death and Dissolution of the Organism 



why it was that the stomach and intestine did not 

 digest themselves. The hydrochloric acid and the 

 pepsin in the stomach and the trypsin in the intestine 

 digest proteins taken in in the form of food; why do 

 they not digest the proteins of the cells of the stomach 

 and the intestine? They will promptly digest the 

 stomach as soon as the individual is dead, but not during 

 life. A self-digestion may also be caused if the arteries 

 of the stomach are ligatured. Claude Bernard and 

 others suggested that the layer of mucus protected 

 the cells of the stomach and of the intestme from the 

 digestive enzymes; or that the epithelial layer had a 

 protective effect. Pavy suggested that the alkali of 

 the blood had a protective action. All these theories 

 became untenable when Fermi showed that all kinds 

 of living organisms, protozoans, worms, arthropods, 

 are not digested in solutions of trypsin as long as they 

 are alive, while they are promptly digested in the same 

 solution when dead.^ This is in harmony with the 

 fact that many parasites live in the intestine without 

 being digested as long as they are alive. Fermi con- 

 cluded that the living cell cannot be attacked by the 

 digestive ferments, while with death a change occurs 

 by which they can be attacked. But what is this 

 change? Fermi seems to be inclined to think that the 

 ''living molecule'* of protein is not hydrolysable (per- 

 haps because the enzyme cannot attach itself to it?), 



' Fermi, C, Centralbl.f. Bacteriologies Abt. i, 1910, Ivi., 55. 



