It is probable that some substance is produced by the cancer which neutralizes the free hydrochloric acid, and thus causes it to disappear earlier than in other organic diseases of the stomach. The presence of lactic acid is the most suggestive single symptom of gastric cancer. In the great majority of cases its presence in notable amount (0.1 per cent. by Strauss' method) after Boas' breakfast, the stomach having been washed the evening before, warrants a diagnosis of malignancy. Carcinoma seems to furnish an especially favorable medium for the growth of the Boas-Oppler bacillus, hence this micro-organism is frequently present. Blood can be detected in the stomach fluid by the chemic tests in nearly one-half of the cases, and is more common when the newgrowth is situated at the pylorus. Blood is present in the stool in nearly every case. Evidences of retention and fermentation are the rule in pyloric cancer. Tumor particles are sometimes found late in the disease. 6. Gastric Ulcer.--There is excess of free hydrochloric acid in about one-half of the cases. In other cases the acid is normal or diminished. Blood is often present. The diagnosis must be based largely upon the clinical symptoms, and where ulcer is strongly suspected, it is probably unwise to use the stomach-tube. {233} II. ADDITIONAL EXAMINATIONS WHICH GIVE INFORMATION AS TO THE CONDITION OF THE STOMACH 1. Absorptive Power of the Stomach.--This is a very unimportant function, only a few substances being absorbed in the stomach. It is delayed in most organic diseases of the stomach, especially in dilatation and carcinoma, but not in neuroses. The test has little practical value. * * * * * Give the patient, upon an empty stomach, a three-grain capsule of potassium iodid with a glass of water, taking care that none of the drug adheres to the outside of the capsule. At intervals test the saliva for iodids by moistening starch-paper with it and touching with yellow nitric acid. A blue color shows the presence of an iodid, and appears normally in ten to fifteen minutes after ingestion of the capsule. A longer time denotes delayed absorption. _Starch paper_ is prepared by soaking filter-paper in boiled starch and drying. * * * * * 2. Motor Power of the Stomach.--This refers to the rapidity with which the stomach passes its contents on into the intestine. It is very important: intestinal digestion can compensate for insufficient or absent stomach digestion only so long as the motor power is good. Motility is impaired to some extent in chronic gastritis. It is especially deficient in dilatation of the stomach due to atony of the gastric wall or to pyloric obstruction, either benign or malignant. It is increased in most conditions with hyperchlorhydria.