156 DIGESTION. 



parts of the glandular apparatus is produced the characteristic secretion 

 of the gastric juice. 



Physical Qualities and Composition of the Gastric Juice. The earliest 

 decisive investigations in regard to the existence and properties of the 

 gastric juice were those made by Dr. Beaumont, of the United States 

 Army, in the case of Alexis St. Martin, a Canadian boatman, who was 

 affected with a permanent gastric fistula, the result of an accidental gun- 

 shot wound. The musket, which was loaded with buckshot at the time 

 of the accident, was discharged, at the distance of a few feet from St. 

 Martin's body, in such a manner as to tear away the integument at the 

 lower part of the left chest, open the pleural cavity, and penetrate, 

 through the lateral portion of the diaphragm, into the great pouch of the 

 stomach. After the integument and the pleural and peritoneal surfaces 

 had united and cicatrized, there remained a permanent opening about two 

 centimetres in diameter leading into the left extremity of the stomach, 

 which was usually closed by a circular valve of protruding mucous 

 membrane. This valve could be readily depressed at any time, so as to 

 open the fistula and allow the contents of the stomach to be extracted 

 for examination. 



Dr. Beaumont experimented upon this person at various intervals 

 from the year 1825 to 1832. 1 He established during the course of his 

 examinations the following important facts : First, that the active agent 

 in digestion is an .acid fluid, secreted by the walls of the stomach; 

 secondly, that this fluid is poured out by the glandular walls of the 

 organ only during digestion, and under the stimulus of the food ; and 

 finally, that it will exert its solvent action upon the food outside the 

 body as well as in the stomach, if kept in glass phials upon a sand-bath 

 at the temperature of 38 (100 F.). He made also a variety of other 

 interesting investigations as to the effect of various kinds of stimulus on 

 the secretion of the stomach, the rapidity with which the process of 

 digestion takes place, and the comparative digestibility of various kinds 

 of food. 



The same person, with his gastric fistula unchanged, after an interval 

 of twenty-four years, came under the observation of Prof. Francis G. 

 Smith, of the University of Pennsylvania, who again made a series of 

 important experiments of a similar nature, confirming and extending 

 those of Dr. Beaumont ; and another case, in a young and otherwise 

 healthy woman, the result of a local inflammation and abscess, happened 

 in Germany in 1854, and was investigated by Prof. C. Schmidt. 



Since Dr. Beaumont's time similar experiments have been frequently 

 performed by means of gastric fistulae artificially established upon the 

 lower animals, especially upon the dog, which has been found most 

 convenient for this purpose ; the result of examinations conducted by 

 this and other methods being that the gastric juice presents the same 

 essential characters in man and in the carnivorous and herbivorous 



1 Experiments and Observations upon the Gastric Juice. Boston, 1834. 



