DIGESTION 301 



When the wound healed a permanent fistulous opening was left, by 

 means of which food could be introduced into the stomach and 

 gastric juice obtained from it. Beaumont at once perceived the 

 possibilities of such a case for physiological research, and began a 

 series of experiments on digestion. After a while, St. Martin, with 

 the wandering spirit of the voyageur, returned to Canada without 

 Dr. Beaumont's consent and in his absence. Beaumont traced him, 

 with great difficulty, by the help of the agents of a fur-trading 

 company, induced him to come back, provided for his family as well 

 as for himself, and proceeded with his investigations. A second 

 time St. Martin went back to his native country, and a second 

 time the zealous investigator of the gastric juice, at heavy expense, 

 s-ecured his return. And although his experiments were necessarily 

 less exact than would be permissible in a modern research, the 

 modest book in which he published his results is still counted 

 among the classics of physiology. The production of artificial 

 fistulae in animals, a method that has since proved so fruitful, was first 

 suggested by his work. 



Gastric juice when obtained pure, as it can be from an 

 accidental fistula in man, or by mechanically stimulating the 

 mucous membrane of the stomach of a fasting dog through 

 an artificial gastric fistula, or, -better, by giving a dog with 

 an cesophageal as well as a gastric fistula a ' sham-meal ' 

 (p. 343), is a thin, colourless liquid of low specific gravity 

 (1002 to 1005) and distinctly acid reaction. The total solids 

 average about 5 parts per thousand, about one half being 

 inorganic salts, chiefly sodium and potassium chloride. Two 

 ferments are present : pepsin, which changes proteids into 

 peptones ; and rennin, which curdles milk. The acidity is 

 due to free hydrochloric acid, the proportion of which in 

 man is usually something like *2 per cent., but more in the 

 dog ('3 to "5 per cent.). Often but not always (Kocher) in 

 cancer of the stomach the free hydrochloric acid is replaced 

 by lactic acid, and it is known that in health some lactic 

 acid is often present when the stomach contains food, being 

 produced from the carbo-hydrates by the action of a ferment 

 or ferments, not specific to gastric juice, but found every- 

 where in the alimentary canal. That in normal gastric 

 juice the acidity is not due to lactic acid can be shown by 

 Uffelmann's test (Practical Exercises, p. 380). 



More than this, it is not due to an organic, but to an 

 inorganic acid, for healthy gastric juice causes such an 

 alteration in the colour of aniline dyes like congo-red and 

 tnethyl violet, as would be produced by dilute mineral acids, 



