The starchy derivatives resulting from the action of the ptyalin-digestion begun in the mouth and continued in the stomach, consist of erythrodextrin, ach-roodextrin, and maltose. A few drops of Lugol's solution (iod. 0.1, potass, iod. 0.2, aq. dest. 200.0) are added to a small quantity of the filtrate. The presence of (9) dextrin turns the fluid blue; (10) erythrodextrin gives rise to a red color. The (11) achroo-dextrin discolors the yellowish tint of the Lugol solu-ion, while (12) maltose does not change the color of the solution. For maltose or sugar, we can besides make use of Trommer's test.

In the healthy condition, the results of the analysis of the stomach contents one to one and a half hours after the test breakfast are as follows: acid reaction; free hydrochloric acid present; lactic acid not present; total acidity varying from 40-00 (=0.015-0.21 per cent hydrochloric acid); propeptone present in small amount; peptone in larger proportions; pepsin and rennet present; sugar present; achroodextrin present; erythrodextrin present in small amounts or absent; dextrin absent. From these normal standards we find manv deviations in the sick, and we shall have to in-vestigate later on the chemical processes in the stomach in all disturbances of this organ.

Although the above tests will suffice for the great majority of cases, we find it necessary to give a few additional methods which are not complicated and which will serve to determine several factors in the gastric analysis more minutely. The acidity of the gastric contents is as a rule due to acid salts, acid compounds of albumin, and free acids (hydrochloric and lactic, and sometimes various organic acids). It is sometimes of importance to ascertain the presence, respectively the quantity, of each of these factors separately.