THE GASTRIC JUICE. 117 



cubic centimeters employed to bring about this reaction, multiplied 

 by 0.00365, indicates the acidity of the 5 or 10 c.c. of gastric juice 

 in terms of hydrochloric acid. 



Amount. The degree of acidity of the gastric juice is usually 

 fairly constant, and in man varies between 0.15 and 0.25 per cent. 

 It is influenced to a certain extent by the character of the food ; for 

 instance, following the administration of a meal rich in proteids, 

 somewhat larger amounts are obtained than after the ingestion of 

 carbohydrates or fats. The smallest amounts are found after the 

 ingestion of water. After Ewald's test-breakfast, which consists of 

 from 35 to 70 grammes of wheat bread and 300 to 400 c.c. of 

 water, or weak tea without sugar, the maximum acidity is reached 

 in about one hour, and corresponds to 1.5 to 1.75 pro mille. Follow- 

 ing the ingestion of liiegePs test-meal, on the other hand, which 

 consists of a plate of soup (400 c.c.), 200 grammes of beefsteak, 50 

 grammes of wheat bread, and 200 c.c. of water, the amount of 

 hydrochloric acid increases to 2.7 pro mille, after from one hundred 

 and eighty to two hundred and ten minutes. In disease still higher 

 figures (5 p. m.) may be observed ; or its secretion may diminish 

 below the normal, and may even cease altogether. 



Hydrochloric Acid. Origin. The hydrochloric acid of the 

 gastric juice is furnished by the so-called parietal, adelomorphous, or 

 oxyntic cells, which are principally found in the glands of the 

 fundu.s. This can be demonstrated by resecting the fundus, then 

 closing one end with a fine suture, and sewing the other into the 

 abdominal wound, while the cardiac portion of the stomach is 

 joined to the pyloric end. If food be now administered to the 

 animal, a fluid will be secreted by the isolated fundus in which the 

 presence of free hydrochloric acid can easily be shown. If, on the 

 other hand, the pyloric end of the stomach, in which no parietal 

 cells are found, is similarly isolated, no acid is obtained, but, instead, 

 a strongly alkaline mucus. 



While it is thus clear that the hydrochloric acid is furnished by 

 the parietal cells, we are as yet ignorant of the mechanism by which 

 this is accomplished. A free acid is manifestly not present in these 

 cells, as can be shown by testing with litmus-paper, or still better by 

 injecting potassium -ferrocyanide and lactate of iron into the circula- 

 tion of an animal, when it will be observed that Berlin-blue is 

 formed in the stomach-cavity, while the cells themselves remain 

 unstained. It thus follows that a substance must either be present 

 in the cells which is capable of yielding hydrochloric acid when 

 secreted to the outside, or a mechanism must exist by which the 

 hydrochloric acid, though formed within the cells, is at once elim- 

 inated. The latter view is now generally held. That the hydro- 

 chloric acid is derived from the chlorides of the blood can be 

 regarded as an established fact. It may thus be secreted even 

 though no food-stuffs have been ingested ; and Kahn, moreover, has 

 shown that animals in which the chlorides of the body have been 



