Gray or black sputum is observed among those who work much in coal-dust, and is occasionally seen in smokers who "inhale."
3. Consistence.—According to their consistence, sputa are usually classified as serous, mucoid, purulent, seropurulent, mucopurulent, etc., which names explain themselves. As a rule, the more mucus and the less pus and serum a sputum contains, the more tenacious it is.
The rusty sputum of croupous pneumonia is extremely tenacious, so that the vessel in which it is contained may be inverted without spilling it. The same is true of the almost purely mucoid sputum ("sputum crudum") of beginning acute bronchitis, and of that which follows an attack of asthma. A purely serous sputum is fairly characteristic of edema of the lungs.
II. MICROSCOPIC EXAMINATION
The portions most likely to contain structures of interest should be very carefully selected, as already described. The few minutes spent in this preliminary examination will sometimes save hours of work later. Opaque, white or yellow particles are frequently bits of food, but may be cheesy masses from the tonsils; small cheesy nodules, derived from tuberculous cavities and containing many tubercle bacilli and elastic fibers; Curschmann's spirals, or small fibrinous casts, coiled into little balls; or shreds of mucus with great numbers of entangled pus-corpuscles.
The sputum should always be examined, both unstained and stained.
A. UNSTAINED SPUTUM
The particle selected for examination should be transferred to a clean slide, covered with a clean cover-glass, and examined with the two-thirds objective, followed by the one-sixth. It is convenient to handle the bits of sputum with a wooden toothpick, which may be burned when done with. The platinum wire used in bacteriologic work is less satisfactory because not usually stiff enough.
The more important structures to be seen in unstained sputum are: elastic fibers, Curschmann's spirals, Charcot-Leyden crystals, fibrinous casts, the ray fungus of actinomycosis, and molds. Pigmented cells, especially the so-called "heart-failure cells" ([p. 43]), are also best studied without staining ([Plate II, Fig. 1]).
| FIG. 4.—Elastic fibers from the sputum: a, Highly magnified; b, alveolar arrangement, less highly magnified (after Bizzozero). |