GASTRIC JUICE. 219 



Impressions made on the nerves of gustation have a marked influence in 

 exciting the action of the mucous membrane of the stomach. Blondlot 

 found that sugar, introduced into the stomach of a dog by a fistula, pro- 

 duced a flow of juice much less abundant than when the same quantity was 

 taken by the mouth. To convince himself that this did not depend upon 

 the want of admixture with the alkaline saliva., he mixed the sugar with 

 the saliva and passed it in by the fistula, when the same difference was 

 observed. In some animals, particularly when they are very hungry, the 

 sight and odor of food will excite secretion of gastric juice. 



A febrile condition of the system, the depression resulting from an excess 

 in eating and drinking, or even purely mental conditions, such as anger or 

 fear, vitiate, diminish and sometimes entirely suppress secretion by the stom- 

 ach. At some times, under these conditions, the mucous membrane becomes 

 red and dry, and at others it is pale and moist. In the morbid conditions, 

 drinks are immediately absorbed, but food remains undigested in the stomach 

 for twenty-four to forty-eight hours (Beaumont). 



After the food has been in part liquefied and absorbed and in part reduced 

 to a pultaceous consistence, the secretion of gastric juice ceases ; the move- 

 ments of the stomach having gradually forced that portion of the food which 

 is but partially acted upon in this organ or is digested only in the small in- 

 testines out at the pylorus. The stomach is thus entirely emptied, the mucous 

 membrane becomes pale, and its reaction loses its marked, acid character, 

 becoming neutral or faintly alkaline. 



Quantity of Gastric Juice. The data for determining the quantity of 

 gastric juice secreted in the twenty-four hours are so uncertain that it seems 

 impossible to fix upon any estimate that can be accepted even as an approxi- 

 mation. Still, the quantity must be considerable, in view of the large quan- 

 tity of alimentary matter which is acted upon in gastric digestion. It is 

 probably not less than six pounds (2- 72 kilos.) or more than fourteen pounds 

 (6-35 kilos.). After this fluid has performed its office in digestion, it is im- 

 mediately reabsorbed, and but a small quantity of the secretion exists in the 

 stomach at any one time. 



Properties and Composition of Gastric Juice. The gastric juice is mixed 

 in the stomach with more or less mucus secreted by the lining membrane. 

 When drawn by a fistula, it generally contains particles of food, which have 

 become triturated and partially disintegrated in the mouth, and is always 

 mixed with a certain quantity of saliva, which is swallowed during the inter- 

 vals of digestion as well as when the stomach is active. By adopting certain 

 precautions, however, the fluid may be obtained nearly free from impurities, 

 except the admixture of saliva. The juice taken from the stomach during 

 the first moments of its secretion, and separated from mucus and foreign 

 matters by filtration, is a clear fluid, of a faint yellowish or amber tint and 

 possessing little or no viscidity. Its reaction is always strongly acid ; and it is 

 now a well established fact that any fluid, secreted by the mucous membrane 

 of the stomach, which is either alkaline or neutral, is not normal gastric juice. 



The specific gravity of the gastric juice in the case of St. Martin, accord- 



