THE GASTRIC JUICE. 127 



From this table it is seen that with a meat diet the maximum 

 secretion occurs in the first and second hours after eating, with bread 

 in the first and milk in the second and third hours. With meat the 

 strongest digestive effect is obtained during the first hour, with 

 bread in the second and third hours, and with milk as late as the 

 fifth and sixth hours. 



The non-digesting stomach of the dog is said to contain no fluid ; 

 in man, however, a small amount of gastric juice can usually be 

 obtained, varying between 1 and 60 c.c. Larger amounts may be 

 found under pathologic conditions, and in the so-called Magen- 

 saftfluss of the Germans it is not rare to find as much as 1000 c.c. 

 in the early morning, before any food has been taken. 



Chemical Composition. A general idea of the chemical com- 

 position of the gastric juice may be formed from the following analy- 

 ses, which are taken from C. Schmidt ; but it is to be noted that 

 the specimen of human gastric juice was contaminated with saliva 

 and somewhat diluted with water (the figures have reference to 1000 

 parts) : 



Acidity of the Gastric Juice. It has been definitely estab- 

 lished that the acidity of normal gastric juice is referable to the 

 presence of free hydrochloric acid, and to this only. This can be 

 shown by estimating the amount of chlorine and all basic substances 

 that are present, when it will be found that after the acid affinities 

 of the latter have been satisfied, a certain amount of chlorine still 

 remains, which can be referable only to hydrochloric acid, and 

 corresponds in its degree of acidity to that of the gastric juice. 



During the process of digestion, however, other factors enter into 

 consideration. In the beginning of digestion lactic acid is always 

 present when carbohydrates form part of the meal. Its amount, 

 however, is then quite small, and after the ingestion of Ewald's 

 test-breakfast, for example, does not exceed 0.3 pro mille. The 

 occurrence of larger quantities of lactic acid, as from 1 to 3 pro 

 mille, is always abnormal, and in many cases indicative of the 

 existence of carcinoma of the stomach. During the later stages 

 of digestion, when hydrochloric acid is found in a free state, lactic 

 acid disappears. Its origin, under normal conditions, is usually 



