| FIG. 115.—Diplococcus pneumoniæ from ulcer of cornea (obj. one-twelfth oil-immersion) (study through courtesy of Dr. C. A. Oliver) (Boston). |
| FIG. 116.—Gonococci in urethral pus (McFarland). |
Gonococci, when typical, can usually be identified with sufficient certainty for clinical purposes in the smear stained with Löffler's methylene-blue. They are coffee-bean-shaped cocci which lie in pairs with their flat surfaces together (Fig. 116). They lie for the most part within pus-cells, an occasional cell being filled with them, while the surrounding cells contain few or none. A few are found outside of the cells. It is not usual to find gonococci when many other bacteria are present, even though the pus is primarily of gonorrheal origin. Whenever the identity of the organism is at all questionable, Gram's method should be tried. In rare instances it may be necessary to resort to cultures. The gonococcus is distinguished by its failure to grow upon ordinary media.
Gonococci are generally easily found in pus from untreated acute and subacute gonorrheal inflammations,—conjunctivitis, urethritis, etc.,—but are found with difficulty in pus from chronic inflammations and abscesses, and in urinary sediments.
PERITONEAL, PLEURAL, AND PERICARDIAL FLUIDS
The serous cavities contain very little fluid normally, but considerable quantities are frequently present as a result of pathologic conditions. The pathologic fluids are classed as transudates and exudates.
Transudates are non-inflammatory in origin. They contain only a few cells, and less than 2.5 per cent. of albumin, and do not coagulate spontaneously. The specific gravity is below 1018. Micro-organisms are seldom present.
Exudates are of inflammatory origin. They are richer in cells and albumin, and tend to coagulate upon standing. The specific gravity is above 1018. Bacteria are generally present, and often numerous. The amount of albumin is estimated by Esbach's method, after diluting the fluid. Bacteria are recognized by cultures, animal inoculation, or stained smears.
Exudates are usually classed as serous, serofibrinous, seropurulent, purulent, putrid, and hemorrhagic, which terms require no explanation. In addition, chylous and chyloid exudates are occasionally met, particularly in the peritoneal cavity. In the chylous form the milkiness is due mainly to the presence of minute fat-droplets, and is the result of rupture of a lymph-vessel. Chyloid exudates are milky chiefly from proteids in suspension, or fine débris from broken-down cells. These exudates are most frequently seen in carcinoma and tuberculosis of the peritoneum.
Cytodiagnosis.—This consists in a differential count of the cells in a transudate or exudate, particularly one of pleural or peritoneal origin.