DIGESTION. 181 



to muscle-fibers, blood-vessels, and glands. In the latter structure 

 terminal arborizations have been detected in close contact with the 

 secreting cells themselves. 



The lymphatics, which are quite numerous, originate in the 

 meshes of the mucosa. The larger trunks enter lymph-glands lying 

 along the greater and lesser curvatures of the stomach. 



Gastric Fistulae. The general process of digestion, as it takes 

 place in the stomach, has been studied in human beings and animals 

 with a fistula in the walls of the stomach and abdomen, the result 

 either of accident or of necessary surgical or experimental procedures. 



The earliest observations on gastric digestion were made by Dr. 

 Beaumont on Alexis St. Martin, who, as the result of a gunshot 

 wound, was left with a permanent fistulous opening into the fundus 

 of the stomach. This opening two years after the accident was about 

 two and a half inches in circumference and usually closed from within 

 by a fold of mucous membrane which prevented the escape of the food. 

 This valve could be readily displaced by the finger and the interior 

 of the stomach exposed to view. After the complete recovery of St. 

 Martin, Dr. Beaumont during the years between 1825 and 1831 at 

 intervals made numerous experiments on the nature of gastric diges- 

 tion. As the result of an admirable series of investigations it was 

 established that the digestion of the food is largely a chemic act, due 

 to the presence of an acid fluid secreted by the mucous membrane; 

 that this fluid is secreted most abundantly after the introduction of 

 food into the stomach; that different articles of food possess varying 

 degrees of digestibility; that the duration of digestion varies according 

 to the nature of the food, exercise, mental states, etc., and that the 

 process is aided by continuous movements of the muscular walls. 



Since Dr. Beaumont's time the establishing of a gastric fistula in 

 human beings has been necessitated by pathologic conditions of the 

 esophagus. After recovery these cases offered fair facilities for the 

 study of the process when the food was introduced through the 

 opening. Similar fistulas have been established in both carnivorous 

 and herbivorous animals with a view of studying the process as it 

 takes place in them. The results obtained in these instances in many 

 respects corroborate those obtained by Dr. Beaumont, though many 

 new facts, unobserved by him, have been brought to light. 



Gastric Juice. The gastric juice obtained from the human 

 stomach free from mucus and other impurities is a clear, colorless 

 fluid with a constant acid reaction, a slightly saline and acid taste, 

 and a specific gravity varying from i.ooTT6~i.oo5. The Jince ob- 

 tained from the dog's stomach possesses essentially the same char- 

 acteristics, though its acidity as well as its specific gravity are slightly 

 greater. When kept from atmospheric influences, it resists putre- 

 factive change for a long period of time, undergoes no apparent 



