THE GASTRIC JUICE. Ill) 



This problem has been carefully investigated, and we now know 

 that the amount of hydrochloric acid which is present at the height 

 of digestion is sufficient at least to arrest the activity of most 

 bacteria which are usually ingested together with food. Some of 

 these, however, are more resistant than others, and among them the 

 lactic acid bacteria are especially stable. We can accordingly under- 

 stand why in the beginning of the process of digestion traces of 

 lactic acid are usually found. So soon, however, as the percen- 

 tage of hydrochloric acid has increased to 0.7 pro mille the activity 

 of these organisms also ceases. Whether or not the gastric juice 

 actually destroys all of the more common micro-organisms that 

 are swallowed has not been determined, but there is evidence to 

 show that in some instances at least the spores remain unaffected 

 and can later develop in the alkaline contents of the sniall intes- 

 tine. In this manner we can account for the presence of the 

 innumerable bacteria which are found in the lower intestinal 

 tract. It must be remembered, moreover, that in the beginning 

 of digestion i. e., when free hydrochloric acid is as yet not pres- 

 ent large numbers of bacteria may also pass through the stomach 

 unaffected, as combined hydrochloric acid possesses no anti-fermenta- 

 tive properties. Some of the more important pathogenic bacteria 

 are unfortunately more resistant than the common benign forms. 

 This is true especially of the tubercle bacillus, and in many cases of 

 the anthrax bacillus and some of the pus organisms, while the 

 cholera bacillus, on the other hand, is readily destroyed. 



Tests for Free Hydrochloric Acid. A large number of tests have 

 been devised for the purpose of demonstrating the presence of free 

 hydrochloric acid in the stomach-contents. At this place only the 

 more important ones will be described, which are employed in the 

 clinical laboratory. 



TOPPER'S TEST. A small amount of the filtered gastric contents 

 is treated with a few drops of a 0.5 per cent, alcoholic solution of 

 dimethyl-amido-azobenzol, when in the presence of free hydro- 

 chloric acid a beautiful cherry-red color develops at once, which 

 varies in intensity with the amount of the free acid present. Com- 

 bined hydrochloric acid, as well as acid salts and organic acids, in 

 the concentration in- which they may be met with in the stomach- 

 contents, does not produce this color. 



The delicacy of the reagent is such that the normal yellow color 

 of the indicator is changed to a reddish tinge upon the addition of 

 but one drop of a T ^ normal solution of hydrochloric acid in 5 c.c. 

 of distilled water, viz., 0.7 per cent. 



GUNZBURG'S TEST. The reagent consists of 2 grammes of phloro- 

 glucin and 1 gramme of vanillin, dissolved in 100 grammes of 

 80 per cent, alcohol. It should be kept in a dark-colored, glass- 

 stoppered bottle. 



A few drops of the filtered gastric contents are carefully evapo- 

 rated with an equal amount of the reagent on a plate of thin poree- 



