294 THE SECRETION OF THE GASTRIC JUICE. 



on the free surface of the mucous membrane, as well as in the excretory 

 ducts of the gastric glands. In the depth of the glandular tubules, 

 however, the reaction is generally alkaline. The acid must, therefore, 

 be advanced rapidly from the depth to the surface. 



Sarcolactic acid can be rapidly extracted as such from the chyme. 

 For the production of lactic acid through fermentation in the stomach it 

 is necessary that the carbohydrates have been present for a consider- 

 able time. This does not occur in the healthy individual, but in asso- 

 ciation with great diminution in the production of hydrochloric acid, 

 stagnation of the ingesta in the stomach, and interference with gastric 

 absorption, particularly in the presence of gastric carcinoma. 



Lactic-acid bacteria are always present in the stomach, though they exhibit 

 no activity in the presence of healthy gastric juice on account of the anti-fermenta- 

 tive influence of the hydrochloric acid. Lactic acid develops, however, only in 

 the absence of free hydrochloric acid, which is particularly often the case in the 

 presence of gastric carcinoma. 



The hydrochloric acid first secreted at once combines in the stomach 

 with the proteids to form acid albumin ates. These do not yield the 

 color-reactions of free acid. As the secretion progresses free hydro- 

 chloric acid makes its appearance. If the secretion of gastric juice be 

 enfeebled it may, therefore, happen that the production of hydrochloric 

 acid is not sufficient to permit of the appearance of free hydrochloric 

 acid. 



When the tests for hydrochloric acid in the stomach-contents are distinctly, 

 even though feebly, positive, sufficient hydrochloric acid is present; an unusually 

 strong reaction is indicative of abnormally increased production. If the reaction 

 is wanting, a decinormal hydrochloric-acid solution is added to a measured amount 

 of gastric contents until a distinct reaction is obtained by Giinzburg's test. The 

 amount of hydrochloric acid consumed is then proportional to the degree of the 

 hydrochloric-acid insufficiency present. 



In regard to the production of free acid, the following appears to be 

 established. The parietal cells secrete hydrochloric acid from the 

 chlorids that the mucous membrane takes up from the blood. There- 

 fore, the production of hydrochloric acid ceases when the chlorids are 

 withdrawn from the food, as well as in the state of hunger. The active 

 agent in this connection has not been discovered; yet it is established 

 that, if carbon dioxid acts continuously on the chlorids, nevertheless, 

 hydrochloric acid is expelled by the much weaker carbon dioxid. Maly 

 and others assume that the production of hydrochloric acid takes place 

 within the parietal cells as follows : 



2Na 2 HPO 4 +3CaCl 2 =Ca 3 (PO 4 ) 2 + 4 NaCl-f2HCl. 



The bases set free by the separation of the hydrochloric acid are 

 excreted in the urine, with the development of a slightly acid reaction. 



When the stomach is empty the gastric juice contains some hydro- 

 chloric acid, but a more abundant secretion is, according to Pawlow, 

 brought about in a most striking manner by the appetite, and also by 

 the stimulation of the food under natural conditions, as well as by 

 water, meat-extractives, and even by indigestible matters when intro- 

 duced into the stomach. Under these circumstances the mucous mem- 

 brane is reddened from increased activity of the circulation, so that the 

 outflowing venous blood is lighter in color. The excitation of the secre- 

 tion is a reflex process. The sensory nerves of the pharynx and the 



