EXAMINATION OF THE DIGESTIVE APPARATUS 23 



juice is much lessened, for there is no doubt that gastric juice can destroy 

 the infectious bacteria that are carried into the stomach by the food; 

 consequently, the secretion thus being much less acid, with the lessened 

 digestion of albvimen, fermentation is easily started. When the gastric 

 secretion is subacid it irritates the mucous membranes of the intestines 

 and lessens the peristaltic action. Subacidity is frequently seen in all 

 anaemic diseases, in fevers, in erosion of the mucous membranes, from 

 the effects of corrosive poisons, in cancer of the stomach, and in chronic 

 catarrh of that organ. 



The digestion of starch is impaired by an oversecretion of hydro- 

 chloric acid; this condition, according to the researches of Ellenberger 

 and Hofmeister, is not of great importance, although in man it is fre- 

 quently seen in ulceration and in acute and chronic catarrh of the 

 stomach. "Nervous dyspepsia," so common in man, does not seem 

 to occur in the dog. 



In testing the contents of the stomach for free hydrochloric acid the 

 best reagent is red paper and phloroglucin-vanillin solution. Moisten 

 a small piece of this paper with a few drops of the filtered fluid-contents of 

 the stomach. If free acid is present the red color of the paper will turn 

 blue. This reaction may also occur if lactic acid is present. This, 

 however, is rarely present in the contents of the stomach. In testing 

 with phloroglucin (vanillin) place a few drops of the following solution: 

 PhloroglucinS parts; vanillin 1 part; alcohol 30 parts; with equal quantity 

 of the filtered fluid of the stomach. Put in a porcelain dish and heat but 

 do not luring to a boil. If there is free hydrochloric acid present, it will 

 produce a dark red precipitate; if it is present in a small amount, the pre- 

 cipitate will be l^right red; if the acid is not present, the precipitate will 

 be brown or reddish-brown. If methyl-violet solution is used, if a trace of 

 free acid is present, it will color the solution sky-blue. The test is made 

 in the following manner: Make a certain quantity of the solution, di- 

 luting the water until it is light violet. Divide this into equal parts put- 

 ting into two test-tubes. To one of the tubes add a few drops of the 

 filtered gastric fluid and if any free acid is present, the solution changes 

 to sky blue and by comparison with the other tube the amount of free 

 acid can be approximated, being guided by the change in the color. 



Testing with lactic acid is much easier and more certain. The best 

 method is that of Uffelman: 100 grammes of a 2 per cent, solution of 

 carbolic acid are to be mixed with one drop of chloride of iron solution, 

 which makes the mixture deep blue; if a few drops of the filtered contents 

 of the stomach are added and muriatic acid only is present, it becomes 

 clear as water; if lactic acid is also present, it becomes greenish-yellow 

 in color. 



In summing up the preceding investigations it is readily seen that 



