On sterilised potatoes they form, in a week to ten days at 37° C., a brown gelatinous layer. Pure cultivations after several generations produce the following results when inoculated into horses, rabbits, guinea-pigs, and field-mice. A spreading ulcer with indurated base appears at the site of inoculation while smaller ulcers break out in its vicinity. The lymphatics become swollen, and general infection follows in the form of nodules in the internal organs,

FIG. 114.-BACILLUS MALLEI, × 1200; from a section of a glanders' nodule.

and nodules and ulcers on the nasal septum. In guinea-pigs a characteristic tumour of the testis, or ovary and vulva, frequently results, and should be prepared for microscopical sections. The bacilli are found in the nodules of the nasal mucous membrane, the lung, spleen, liver, and other organs in horses and sheep affected with glanders.

METHODS OF STAINING THE BACILLUS OF GLANDERS.

The bacilli of glanders are extremely difficult to demonstrate. The most satisfactory results are obtained as follows:

Method of Schütz.-The sections are placed for twentyfour hours in a mixture of

Potash solution (1 in 10,000);

) Equal

Concentrated alcoholic methylene-blue solution ; parts.

Wash the sections in a watch-glass with water acidulated with four drops of acetic acid. Transfer for five minutes to 50 per cent. alcohol, fifteen minutes to absolute alcohol, clarify in clove oil, and mount in Canada balsam.

In

Bacillus oedematis maligni, Koch (Pasteur's Septicemia).—Rods from 3—3'5 μ long and I-II μ wide; they mostly lie in pairs, and then appear to be double this length. The rods are rounded at their ends, and form threads which are sometimes straight, but more commonly curved. stained preparations they have a somewhat granular appearance. The bacilli are distinguished from anthrax bacilli by their being somewhat thinner, by their rounded ends, and by their being motile. Anthrax bacilli also never appear as threads in fresh blood, and are differently distributed throughout the body. They are anaerobic, and can be cultivated on blood serum and on neutral solution of Liebig's meat extract in an atmosphere of carbonic acid. By embedding material containing bacilli in nutrient agar-agar and nutrient gelatine, characteristic cultivations are obtained. The following process may be adopted to obtain a pure cultivation.* A mouse inoculated subcutaneously with dust, as a rule, dies in one to two days. It is then pinned out, back uppermost, on a slab of wood (p. 141), and the hair singed with a Paquelin's cautery from one hind leg up to the neck, across

Hesse, Deutsch. Med. Woch, No. 14. 1885.

the latter, and down again to the opposite hind leg. Following the cauterised line, the skin is cut through with sterilised scissors, and the flap turned back and pinned out of the way. With curved scissors little pieces of the subcutaneous œdematous tissue, in the neighbourhood of the inoculated spot, are cut out, and sunk with a platinum needle in a 1 per cent. nutrient agar-agar, or 5 per cent. nutrient gelatine. Fragments of tissue may also be embedded by the method already described (p. 167).

The inoculated tubes are placed in the incubator. In a few hours a whitish turbidity spreads out from the piece of tissue, and upwards in the needle track. Examined microscopically, the turbidity is found to be due solely to the development of bacilli of œdema. The surface exposed to the air exhibits no trace of the bacilli.

In

To investigate the tubes microscopically, a sterilised glass tube with a capillary end may be used, with its neck plugged with sterilised cotton-wool, and provided at the mouth with a suction ball. The capillary end is thrust into the cultivation, and a small fragment removed by aspiration. the course of the first day the bacilli spread throughout a great part of the agar-agar in such a way that a more or less equally diffused cloudiness of the medium ensues, with subsequent appearance of strongly marked clouds or lines of turbidity. At the same time gas-bubbles develop along the needle

track, and a collection of liquid takes place, while spore-formation also commences. The following day these appearances are more marked, the opacity is more pronounced, the development of gas increases, and the liquid contains more spore-forming bacilli and numerous free spores.

The nutrient-gelatine cultures during the first day show no macroscopic change, but after a few days the piece of tissue is surrounded with a white halo. This gradually spreads in all directions, and is apparently beset with hairs. The gelatine liquefies, and the fragment of tissue, degenerated bacilli, and spores, sink to the bottom. The cultivation is also very characteristic in per cent. nutrient agaragar. If placed in the incubator, in a few hours a cloudiness forms around the piece of embedded tissue, which is caused by bacilli gradually spreading in all directions in the nutrient medium. Mice inoculated from these cultivations die more quickly than from the original infection from dust. On potatoes they are cultivated by introducing a piece of liver or other tissue containing the bacilli, into the interior of a sterilised potato (p. 143), incubated at 38° C. The bacillus is not deprived of its virulence by cultivation. The spores of the oedemabacilli appear to be very widely distributed. They are found in the upper cultivated layer of the soil, in hay dust, in decomposing liquids, and especially in the bodies of suffocated animals, which are left to decompose at a high temperature. From From any of

these sources animals can be successfully inoculated. If a guinea-pig, for example, be subcutaneously inoculated with earth, putrid fluid, or hay dust, death frequently occurs in from twenty-four to forty-eight hours. At the autopsy the most characteristic symptom is a widespread subcutaneous œdema, which originates from the point of inoculation, accompanied with air-bubbles, and contains a clear reddish liquid full of motile and non-motile bacilli. The internal organs are little changed, the spleen is enlarged and of a dark colour, and the lungs are hyperæmic, and have hæmorrhagic spots. Examined immediately after death, few or no bacilli are detected in the blood of the heart, but in that of the spleen, liver, lungs, and other organs, in the peritoneal exudation, and in and upon the serous coating of abdominal organs they are present in large numbers. If, on the other hand, the animal is not examined until some time after death, then the bacilli are found in the blood of the heart, and distributed all over the body.

Bacillus of septicemia of mice, Koch.Extremely minute bacilli, 8—1 μ long, and 1-2 μ broad, often in pairs, seldom in chains of four. On cultivation they do not appear to make threads, but the bacilli lie together in masses. Spores have been observed. The bacilli are probably nonmotile. They are most commonly in the interior of white blood corpuscles. In these they increase, and in many cases a white cell is only represented