The best evidence of deficient motor power is the detection of food in the stomach at a time when it should be empty, _e.g._, before breakfast in the morning. When more than 60 c.c. of fluid are obtained with the tube one hour after a Ewald breakfast, deficient motility may be inferred. * * * * * {234} Ewald's salol test is scarcely so reliable as the above. It depends upon the fact that salol is not absorbed until it reaches the intestine and is decomposed by the alkaline intestinal juices. The patient is given 15 grains of salol with a test-breakfast, and the urine, passed at intervals thereafter, is tested for salicyluric acid. A few drops of 10 per cent. ferric chlorid solution are added to a small quantity of the urine. A violet color denotes the presence of salicyluric acid. It appears normally in sixty to seventy-five minutes after ingestion of the salol. A longer time indicates impaired motor power. * * * * * 3. To Determine Size and Position of Stomach.--After removing the test-meal, while the tube is still in place, force quick puffs of air into the stomach by compression of the bulb. The puffs can be clearly heard with a stethoscope over the region of the stomach, and nowhere else. If desired, the patient may be given a dram of sodium bicarbonate in solution, followed immediately by the same amount of tartaric acid, also in solution; or he may take the two parts of a seidlitz powder separately. The carbon dioxid evolved distends the stomach, and its outline can easily be determined by percussion. {235} CHAPTER V THE FECES As commonly practised, an examination of the feces is limited to a search for intestinal parasites or their ova. Much of value can, however, be learned from other simple examinations, particularly a careful inspection. Anything approaching a complete analysis is, on the other hand, a waste of time for the clinician. The normal stool is a mixture of--(_a_) Water; (_b_) undigested and indigestible remnants of food, as starch-granules, particles of meat, plant-cells and fibers, etc.; (_c_) digested foods, carried out before absorption could take place; (_d_) products of the digestive tract, as altered bile-pigments, mucus, etc.; (_e_) products of decomposition, as indol, skatol, fatty acids, and various gases; (_f_) epithelial cells shed from the wall of the intestinal canal; (_g_) harmless bacteria, which are always present in enormous numbers. Pathologically, we may find abnormal amounts of normal constituents, blood, pathogenic bacteria, animal parasites and their ova, and biliary and intestinal concretions. The stool to be examined should be passed into a clean vessel, without admixture of urine. The offensive odor can be partially overcome with turpentine or 5 per cent. phenol. When search for _Amoeba coli_ is to be made, the vessel must be warm, and the stool kept warm until examined; naturally, no disinfectant can be used.