CHAPTER IX. 



ACTION OF THE GASTRIC JUICE IN DIGESTION. 



Constituents on which the activity of the gastric juice depends Action of the 

 gastric juice upon meats Action upon albumen, fibrin, caseine, and gelatine 

 Action upon vegetable nitrogenized principles Albuminose, or peptones 

 Action of the gastric juice on fats Action on saccharine and amylaceous prin- 

 ciples Duration of stomach-digestion Digestibility of different aliments in 

 the stomach Action of the gastric juice upon the coats of the stomach 

 Circumstances which influence stomach-digestion. 



IN treating of the composition of the gastric juice, frequent 

 allusion has been made to its solvent action in digestion, and 

 the constituents on which this property depends. Certain 

 of the principles most readily attacked by this fluid are acted 

 upon by weak acid solutions containing no organic matter ; 

 but though some physiologists have been disposed to regard 

 the acts of solution which take place in the stomach as de- 

 pendent merely on the presence of a free acid, it is now well 

 established that the presence of a peculiar organic principle 

 is an indispensable condition to the performance of real di- 

 gestion by the gastric fluid. 1 The experiments of Mialhe, 2 



1 BOUCHARDAT ET SANDRAS, Recherches sur la Digestion. Annales de Chimie et 

 de Physique, 1842, 3me serie, tome v., p. 478 et seq. These authors attempted to 

 show that a feeble acid fluid was capable of dissolving fibrin and gluten, but they 

 failed to prove that this solution was similar to the process which takes place 

 in digestion. The view that the digestion of certain principles in the stomach 

 is due solely to the action of a free acid was also entertained by Tiedmann and 

 Gmelin. (Op. tit.) 



3 MIALHE, Chimie appliquee d la Physiologie et d la Therapeutique, Paris, 1856, 

 p. 114 et seq. In these experiments, Mialhe was only carrying out the idea of 

 Dumas, who believed that two agents exist in the gastric juice ; viz., "the acid 



