ACTION OF THE GASTRIC JUICE UPON THE STOMACH. 281 



linity of the blood, why animal tissues are digested in the 

 alimentary canal, while the coats of the canal itself are pro- 

 tected ? Taking into consideration all the facts relating to 

 this subject, the following seem to be the most rational con- 

 clusions : 



Although, during life, the secretions discharged into the 

 alimentary canal will digest the various articles of food with- 

 out attacking the canal itself, after death, the accumulation 

 in the stomach is frequently sufficient to digest the coats of 

 the organ, causing perforation and escape of its contents, 

 and acting sometimes upon contiguous parts. The accu- 

 mulation in the jejunum, where intestinal digestion is most 

 active, is never considerable ; for digestion is here complete 

 and rapid, and absorption follows immediately. It is impos- 

 sible to say whether, if the digestive fluids should remain in 

 quantity in this part after death, post mortem digestion of 

 the intestines would or would not take place. 



In the living stomach, the circulation of a great quantity 

 of an alkaline fluid is an effectual barrier to the solution of 

 its tissues by the gastric juice ; for acidity is an indispensable 

 condition to the action of this fluid upon any substance. This 

 condition of the tissues would not, however, protect the walls 

 of the small intestine from the action of the alkaline fluids 

 poured into its cavity. 



Inasmuch as digestion involves a catalytic transformation 

 of alimentary principles into new substances with distinctly 

 modified properties, it necessarily abolishes, for the time, 

 all other catalytic processes. For this reason the cata- 

 lytic changes incident to putrefaction are arrested by the 

 action of the gastric juice, the more powerful process of 

 transformation into albuminose, or peptones, taking its place. 

 It is impossible that the digestive fluids should act upon any 

 living part in which the catalytic changes incident to nutri- 

 tion are so actively in operation as in the mucous membrane 

 lining the alimentary canal ; for these involve a constant sup- 

 ply of new material, with removal of effete matter, which 



