36 DISEASES OF THE DIGESTIVE APPARATUS. 



la testing the contents of the stomach for free hydrochloric 

 acid the best reagent is tropseolia paper and phloroglucin-vanillin 

 solution. Moisten a small piece of this paper with a few drops 

 of the filtered fluid-contents of the stomach, and it is then placed 

 in a watch-glass and slowly heated; if muriatic acid is present, it 

 will turn lilac; if the acid is in large quantities, the paper will 

 color without heating. In testing with phlorogluciii (vanillin) 

 place a few drops of the following solution: Phloroglucin, 3 parts; 

 •vanillin, 1 part; alcohol, 30 parts, with an equal quantity of the 

 filtered fluid of the stomach. If there is free hydrochloric acid 

 present, it will produce a dark red precipitate; if it is present in 

 small amount, the precipitate will be bright red; if the acid is 

 not present, the precipitate will be brown or reddish-brown. Un- 

 fortunately this test is not reliable with either of the above reagents 

 if albumin or phosphates are present in any quantity. 



Testing for lactic acid is much easier and certain. The best 

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

 tion 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. 



la summing up the preceding investigations it is readily seen 

 that the stomach may not be digesting all that the animal eats, 

 but still the animal be in fairly good health; while, of course, 

 it must be also understood that in fevers or any general disturb- 

 ance the digestive powers are greatly impaired. 



Albumin is almost entirely digested in the intestines, the stomach 

 merely preparing it; fat and starch are digested only in the smull 

 intestines; muscular tissue must have a previous preparation in 

 the stomach, or if it reaches the small intestines without becoming 

 saturated with gastric juice it is not digested in the intestines. 

 No digestion whatever takes place in the large intestines. 



No animal vomits easier than the dog, and it may be produced 

 from a number of causes, as a reflex irritation of the stomach, viz. : 



1. By irritation of the mucous membranes of that organ by 

 emetics, poisons, splinters of bone, or even by overloading. Vom- 

 iting frequently is caused by the animal eating grass. 



2. By sympathetic irritation from other organs, nephritis, 



