5. Actinomyces Bovis (Ray-fungus).--In the sputum of pulmonary actinomycosis and in the pus from actinomycotic lesions elsewhere small, yellowish, "sulphur" granules can be detected with the unaided eye. The fungus can be seen by crushing one of these granules between slide and cover, and examining with a low power. It consists of a network of threads having a more or less radial arrangement, those at the periphery presenting club-shaped extremities (Fig. 8). This organism, also called _Streptothrix actinomyces_, apparently stands midway between the bacteria and the molds. It stains by Gram's method. {32} Actinomycosis of the lung is rare. The clinical picture is that of tuberculosis. 6. Molds.--The hyphæ and spores of various molds are occasionally met with in the sputum. They are usually the result of contamination, and have little significance. The hyphæ are rods, usually jointed or branched (Fig. 58), and often arranged in a meshwork (mycelium); the spores are highly refractive spheres. Both stain well with the ordinary stains. B. STAINED SPUTUM Structures which are best seen in stained sputum are bacteria and cells. 1. Bacteria.--Only those of some clinical importance will be considered. They are: tubercle bacilli; staphylococci and streptococci; pneumococci; bacilli of Friedländer; and influenza bacilli. (1) Tubercle Bacillus.--The presence of the tubercle bacillus may be taken as positive evidence of the existence of tuberculosis somewhere along the respiratory tract, most likely in the lung. In laryngeal tuberculosis they are not easily found in the sputum, but can nearly always be detected in swabs made directly from the larynx. Recognition of the tubercle bacillus depends upon the fact that it stains with difficulty; but that when once stained, it retains the stain tenaciously, even when treated with a mineral acid, which quickly removes the stain from other bacteria. The most convenient method for general purposes is here given in detail: * * * * * Gabbet's Method.--(1) Spread suspicious particles thinly and evenly upon a slide or a cover-glass held in the grasp of {33} cover-glass forceps. Cover-glasses are easier to handle while staining. Do not grasp a cover too near the edge or the stain will not stay on it well. Tenacious sputum will spread better if gently warmed while spreading. (2) Dry the film in the air. (3) Fix in a flame; _i.e._, pass the cover-glass rather slowly, with film side up, three times (a slide about twelve times) through the flame of a Bunsen burner or alcohol lamp. Take care not to scorch. Should the film be washed off during future manipulations, fixation has been insufficient. (4) Apply as much carbol-fuchsin as will stay on, and hold over a flame so that it will steam for three minutes or longer, replacing the stain as it evaporates. If the bacilli are well stained in this step, there will be little danger of decolorizing them later. (5) Wash the film in water.