252 DIGESTION. 



undertaken with the view of showing that the acid simply 

 prepared the albuminoids by permeating them and causing 

 them to swell up and become gelatiniform, do not show that 

 solution of these principles, even after such preparation, can 

 be accomplished by a neutral solution of the organic princi- 

 ple of the gastric juice. The view thus advanced by Mialhe 

 was completely disproved by the observations of Longet, 

 who showed that when the solution was neutralized, some of 

 the acid fluid always remained in the substance of the nitro- 

 genized principle which had been subjected to its action; 

 and thus, when pepsin was added, the substance digested 

 was really permeated by a fluid containing both the organic 

 principle of the gastric juice and an acid. "When, on the 

 other hand, the fibrin, which was the nitrogenized substance 

 used in the experiments, was removed from the neutralized 

 solution, cut into slices, and washed, so as to remove. all trace 

 of acid, the neutral solution of pepsin had no action upon it. 1 



It has, indeed, been fully established that fluids contain- 

 ing the organic principle of the gastric juice have no diges- 

 tive properties unless they also possess the proper degree of 

 acidity ; and it is as well settled that fluids containing acids 

 alone have no action on albuminoids similar to that which 

 takes place in digestion ; and that when these principles are 

 dissolved by them it is simply accidental. 



It is a curious fact that the presence of any one particu- 

 lar acid does not seem essential to the digestive properties 

 of the gastric juice, so long as the proper degree of acidity 

 is retained. In the experiments of Bernard, Villefranche, 

 and Barreswil, after saturating the gastric juice with neu- 



wlrich softens and swells up the nitrogenized matter ; the pepsin or the chymo- 

 sine which determines its liquefaction by a phenomenon analogous to that of the 

 action of diastase on starch." (Traite de Chimie, Paris, 1846, tome vi., p. 380.) 

 This opinion of Dumas is based on experiments showing that fibrin is reduced to 

 a jelly-like consistence by the action of six parts of hydrochloric acid with ten 

 thousand parts of water, and is afterward completely dissolved by adding to the 

 mixture a few drops of rennet. 

 1 LONGET, op. cit., p. 214. 



