CHAPTER X.

TYPHUS MURIUM.

THE Bacillus typhi murium (Fig. 113), which created havoc among the mice in his laboratory, causing most of them to die, was discovered by Löffler in 1889. It is a short organism, somewhat resembling the bacillus of chicken-cholera. It is rather variable in its dimensions, and often grows into long, flexible filaments.

No

FIG. 113.-Bacillus typhi murium, from agar-agar; × 1000 (Itzerott and Niemann).

sporulation has been observed. It is a motile organism, with numerous flagella, like those of the typhoid-fever bacillus. It stains well with the ordinary dyes, but rather better with Löffler's alkaline methylene blue.

Upon gelatin plates the deep colonies are at first round, slightly granular, transparent, and grayish. Later they become yellowish-brown and granular. Superficial colonies are similar to those of the typhoid bacillus. In

gelatin punctures there is no liquefaction. The growth takes place upon the surface principally, where a grayishwhite mass slowly forms.

Upon agar-agar a grayish-white development devoid of peculiarities occurs.

Upon potato a rather thin whitish growth may be observed after a few days.

The bacillus grows well in milk, with the production of an acid reaction, but without coagulation.

The organism is pathogenic for mice of all kinds, which succumb in from one to two days when inoculated subcutaneously, and in eight to ten or twelve days when fed upon material containing the bacillus. The bacilli multiply rapidly in the blood- and lymph-channels, and cause death from a general septicemia.

Löffler expressed the opinion that this bacillus might be of use in ridding infested premises of mice, and the results of its use for this purpose have been highly satisfactory. He has succeeded in ridding a field so infested as to be useless for agricultural purposes by saturating some bread with bouillon cultures of the bacillus and distributing it near the holes inhabited by the mice. The bacilli that were eaten by the mice not only killed them, but also infected others which ate the dead bodies of the first victims, and so the extermination progressed until scarcely a mouse remained in the field. The bacilli are not pathogenic for the animals, such as the fox, weasel, ferret, etc., that feed upon the mice, do not affect man in any way, and so seem to occupy a useful place in agriculture by destroying the little but almost invincible enemies of the grain.

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