will be found to be composed of necrotic material containing leucocytes and fragments of chromatin. The distribution and extent of the lesions vary with each animal, but the involvement of the testis or its membranes is practically constant and pathognomonic of the bacillus of glanders. This involvement of the testis may consist, in early cases, in the presence of yellow foci in or about the tunica vaginalis, or in later cases the organ may show large yellow areas with purulent softening.

Intraperitoneal inoculation with virulent cultures may be followed by death within forty-eight hours, with fibrinous exudate on the peritoneum in which minute grayish nodules are seen. The nodules are made up of a material which is apparently mainly dead or degenerated leucocytes and desquamated peritoneal endothelium, together with many chromatin fragments.

In these acute cases also microscopical examination of the spleen and liver may show the presence of small nodules identical in structure with those seen in the more chronic cases. For the purpose of producing with cultures the characteristic lesions of the testis or its coverings it is better to inoculate the animal subcutaneously, for in the rapidly fatal intraperitoneal inoculations with virulent cultures these may not show any marked changes.

The bacilli may be cultivated from the lesions, but not from the blood of the heart, in the chronic cases. They may be present in the blood of the heart, however, in small numbers in rapidly fatal infections following intraperitoneal inoculation.

Field-mice may die from subcutaneous inoculation in about seventy-two hours. The most conspicuous lesion produced is enlargement of the spleen, with the presence in it of minute grayish nodules. White mice are immune. Rabbits are not so susceptible as guinea-pigs to the infection. Decolorized by Gram's method. Not motile. Sporeformation not probable. Rate of growth is slow.

Bouillon.-Diffusely clouded, with the formation of a viscid sediment.

Litmus-milk.-Gradually turned red and coagulated.
Agar-agar and Gelatin.-Growth not especially charac-

teristic.

Occurrence.-Found in the lesions of glanders, and may invade the blood-stream in small numbers in acute cases of infection. Grows in the tissues in clumps or groups as well as scattered. In lesions on exposed surfaces it may be accompanied by the pyogenic cocci.

Bacillus Proteus (Proteus Vulgaris).-MorphologyBacilli of very variable length, sometimes appearing like cocci or as filaments.

Motile, being provided with terminal flagella. Does not stain by Gram's method.

Colonies in Gelatin.-Rapid growth with liquefaction of the gelatin. In a medium containing 5 per cent., instead of 10 per cent., of gelatin prolongations from the margins of the colonies may be formed. These may become separated from the mother colonies and form daughter colonies. Motions may be observed in these prolongations.

Gelatin Stab.-Rapid liquefaction along the line of inoculation with cloudiness of the liquefied gelatin and a flocculent deposit.

Agar-agar Slant.-Widely spreading, thin, moist, grayishwhite layer.

Potato.-Dirty white, moist layer.

Litmus-milk.-Turned pink and slowly coagulated.

Odor. The cultures generally have a putrefactive odor. Pathogenesis. Intravenous, intraperitoneal, or intramuscular inoculations of rabbits may produce death in twentyfour to thirty-six hours after moderately large doses. Liquefied gelatin-cultures are said to be more virulent than bouillon cultures. Guinea-pigs seem to be less susceptible than rabbits to infection with this organism.

Occurrence. This bacillus and its varieties are among the most common and widely distributed putrefactive bacteria. It occurs in the intestinal contents. In pathological examinations it may be found in peritonitis and in abscesses,

usually associated with other bacteria. It may also invade the circulating blood.

The so-called "proteus group" includes several varieties of similar organisms-viz. the proteus vulgaris, the proteus mirabilis, and the proteus Zenkeri. The latter does not liquefy the gelatin, while the proteus mirabilis liquefies it slowly.

Bacillus Mucosus Capsulatus.'-Blood-serum.-After twenty-four to thirty-six hours in the incubator the colonies appear as translucent, colorless, rounded, convex elevations,

FIG. 64.-Bacillus mucosus capsulatus, from the sputum of a pneumonia patient; X 1000 (Fränkel and Pfeiffer).

resembling drops of mucus.

If few in number, they may
They are viscid, and when

attain a diameter of 2-3 mm. touched with the platinum wire may be drawn out into threads. The water of condensation may become thick or viscid from the growth of the organism in it.

Morphology.-Bacilli of moderate size, usually two or three times as long as broad, with rounded ends, occurring frequently in pairs and sometimes in long forms. Occasionally in cultures it shows a wide capsule. The capsule, how

1 Friedländer: Fortschritte der Medicin, 1883, Bd. 1. S. 715; C. Fricke: Zeitschrift f. Hygiene u. Infectionskrankheiten, Bd. 23, 1896.

ever, is best shown in cover-glass preparations from infected tissues (Figs. 64, 65).

Pathogenesis.-White mice, rabbits, and guinea-pigs die from septicemia in a short time after inoculation, the capsule bacilli being present in the organs and blood of the heart in large numbers.

White mice die in twenty-four hours to three days. Rabbits inoculated in the ear-vein and guinea-pigs inoculated in the peritoneal cavity may die within twenty-four hours.

Subcutaneous inoculation of the animals last named

leads only to local suppuration. The lesions produced by this organism consist in marked congestion of the superficial veins, hemorrhage into the lymphatic glands, and enlargement and softening of the spleen. In the guinea-pig a hemorrhagic condition of the supra-renal capsules is present, and in the peritoneal cavity there may be a small amount of clear, rather viscid fluid containing the bacilli in large numbers.

The organs on microscopic examination may show peculiar areas in which the cells and nuclei are shrunken and in which the bacilli are aggregated.

Decolorized by Gram's method. Not motile. Does not form spores.

Glucose Agar-agar Stab.-Growth along the line of inoculation, with the production of a few gas-bubbles in the medium. Bouillon. Clouded with the formation of a thin pellicle. Potato.-Thin, colorless, viscid layer.

Litmus-milk.-Turned red and coagulated.
Gelatin.-Growth not remarkable.

There apparently exists a number of varieties of aërobic capsulated bacilli differing from one another only in non-essential particulars. The organism here described is to be taken as a type of a group of closely-related bacteria of which the bacillus pneumonia of Friedländer is a well-known member.

Occurrence. This organism or closely related forms may be met with in broncho- or lobular pneumonia and in inflam

It may

FIG. 66.-Bacillus of tetanus; X 1000 (Fränkel and Pfeiffer). matory conditions of the air-passages generally. also be present in the upper air-passages of healthy individuals. It has been observed in inflammations of the middle ear, in empyema, meningitis, endocarditis, peritonitis, and in pus-formations. In fatal infections the blood-stream may be found invaded by the organism. It is held by some bacteriologists that the members of this group may be the infective agents in genuine croupous pneumonia in rare instances.