Under normal conditions little is to be seen except great numbers of starch-granules, with an occasional epithelial cell, yeast-cell, or bacterium. Starch-granules are recognized by their concentric striations and the fact that they stain blue with iodin solutions. [Illustration: FIG. 88.--General view of the gastric contents: _a_, Squamous epithelial cells from esophagus and mouth; _b_, leukocytes; _c_, cylindric epithelial cells; _d_, muscle-fibers; _e_, fat-droplets and fat-crystals; _f_, starch-granules; _g_, chlorophyl-containing vegetable matters; _h_, vegetable spirals; _i_, bacteria; _k_, sarcinæ; _l_, budding (yeast) fungi (Jakob).] Pathologically, remnants of food from previous meals, red blood-corpuscles, pus-cells, sarcinæ, and excessive numbers of yeast-cells and bacteria may be encountered (Fig. 88). Remnants of food from previous meals indicate deficient gastric motility. Red Blood-corpuscles.--Blood is best recognized by the chemic tests already given. The corpuscles {229} sometimes retain a fairly normal appearance, but are generally so degenerated that only granular pigment is left. Pus-cells.--Pus is rarely encountered in the fluid removed after a test-meal. Considerable numbers of pus-corpuscles have been found in some cases of gastric cancer. Swallowed sputum must always be considered. Sarcinæ.--These are small spheres arranged in cuboid groups often compared to bales of cotton. They frequently form large clumps and are easily recognized. They stain brown with iodin solution. They signify fermentation. Their presence is strong evidence against the existence of gastric cancer, in which disease they rarely occur. Yeast-cells.--As already stated, a few yeast-cells may be found under normal conditions. The presence of considerable numbers is evidence of fermentation. Their appearance has been described (p. 130). They stain brown with iodin solution. [Illustration: FIG. 89.--Boas-Oppler bacillus from case of gastric cancer (Boston).] Bacteria.--Numerous bacteria may be encountered, especially in the absence of free hydrochloric acid. The _Boas-Oppler bacillus_ is the only one of special significance. {230} It occurs in the majority of cases of cancer, and is rarely found in other conditions. Carcinoma probably furnishes a favorable medium for its growth. These bacilli (Fig. 89) are large (5 to 10 µ long), non-motile, and usually arranged end to end in chains. They stain brown with iodin solution, which distinguishes them from _Leptothrix buccalis_ (p. 270), which is not infrequently found in stomach fluid. They also stain by Gram's method. They are easily seen with the one-sixth objective in unstained preparations, but are best recognized with the one-twelfth, after drying some of the fluid upon a cover-glass, fixing, and staining with Löffler's methylene-blue or by Gram's method.