THE ALUMNI JOURNAL. 



cose, and acts most readily on cooked 

 starch. This action does not entirely 

 cease in the stomach, although it is 

 very slight in this organ. 



After the bolus of food has been prop- 

 erly masticated and insalivated, it passes 

 down the oesophagus and into the stom- 

 ach. (CE^ophagus is 9 in. long. Deg- 

 lutition 6 seconds). 



The stomach is a pear-shaped organ, 

 situated immediately under the dia- 

 phragm. It has a capacity of about 5 

 pints, and consists of three layers of tis- 

 sue— the outer a smooth serous mem- 

 brane, which prevents friction, a middle 

 or muscular coat, which gives it its con- 

 tractibility, and an inner or mucous coat, 

 which contains the cells that secrete the 

 gastric juice. 



These cells are of two kinds — one 

 'Called acid cells, that secrete the hydro- 

 chloric acid, and the other called peptic 

 cells, that secrete the pepsin. According 

 to more recent observations the so-called 

 peptic cells secrete an element that is 

 known as pepsinogen, and this is con- 

 verted into pepsin by its contact with the 

 hydrochloric acid. 



Little was known of the chemical ac- 

 tion of this important digestive fluid un- 

 til the experiments of Beaumont, made 

 on St. Martin during a period extend- 

 ing from 1825 to 1832. St. Martin was 

 a trapper, who followed his calling in the 

 northern part of this State, and it was while 

 in pursuit of game that his hunting- 

 piece was accidentally discharged, inflict- 

 ing an injury of the wall of the abdomen 

 and tearing away a portion of the stom- 

 ach. When the patient recovered a fistu- 

 lous opening remained between the stom- 

 ach's interior and the external air, and 

 thus it was possible for Beaumont, who 

 had the man under observation'for a long 

 time, to make careful analysis of the con- 

 tents of the stomach from time to time. 

 Since then artificial gastric fistulae have 



been frequently established in the lower 

 animals, and it was in this manner that 

 the specimen of gastric juice I now pre- 

 sent to you was obtained. 



The operation is not a difficult one, 

 but it is not necessary to discuss it here. 

 During the intervals of digestion the 

 inner surface of the stomach is covered 

 by a layer of thick alkaline mucous, 

 which gives the mucous membrane a 

 pale, slimy appearance. When food is 

 introduced it acts as a stimulus to the 

 gastric cells, and the freshly secreted 

 juice washes this coating away. The 

 membrane then presents a red conjested 

 appearance with small streams of clear 

 gastric juice running down its sides. 



The quantity of gastric juice secreted 

 in twenty-four hours is variable and diffi- 

 cult to measure. It is a sure estimate to 

 say that no less than six, no more than 

 fourteen pounds are secreted in a single 

 day. It is of clear amber color (this 

 specimen has been filtered through ani- 

 mal charcoal — to get a fresh specimen, if 

 possible), is of strongly acid reaction, 

 and contains free hydrochloric acid and 

 pepsin. 



This specimen was drawn on Novem- 

 ber 3, and, as you see, is still acid and 

 has not undergone decomposition. The 

 activity of this digestive fluid depends 

 upon pepsin, and the hydrochloric acid. 

 Still other acids may be substituted with- 

 out interfering with its efficacy. 



Action of Gastric Juice. — The bo- 

 lus of food passes down the oesophagus 

 from the mouth. The saliva continues 

 its action in starch in the presence of the 

 gastric juice, but only to a very slight 

 degree. 



The gastric juice converts meat, cas- 

 erne and the other albumenoids, or what 

 we have classified as the organic nitro- 

 genized elements of diet, into acid pep- 

 tones. But this class of foods is not en- 

 tirely digested in the stomach. 



