524 BACILLI WHICH PRODUCE SEPTICZMIA 
BACILLUS OF LASER. 
Obtained by Laser (1892) from mice which succumbed to an epidemic dis 
ease in Frinkel’s laboratory at Kénigsberg. : . 
In its characters this bacillus closely resembles the bacillus of swine 
plague, and is perhaps identical with it. ’ 
Morphology.—A small bacillus, with rounded ends, about twice as long 
as broad. Has flagella both at the extremicies and sides. 
Stains by the usual aniline colors and also by Gram’s method. 
Biological Characters.—An_ aérobie and facultative anaérobic, non- 
liquefying, actively motile bacillus. Spore formation not observed. Grows 
either in the incubating oven or at the room temperature, Thermal death- 
point 65° to 70° C.—ten minutes’ exposure. Upon gelatin plates, at the end 
of two days, the deep colonies are spherical, finely granular, and brownish 
in color; the superficial are transparent, finely granular, and leaf-like. 
In gelatin stab cultures growth occurs along the entire line of puncture as 
well as upon the surface. At the end of three days a considerable evolution 
of gas is usually observed. In agar an abundant development is seen at the 
oni of twenty-four hours in the incubating oven; upon the surface a gray- 
ish-white, shining layer with dentate margins is formed along the track of 
the needle. In bouillon, at 37° C., development is abundant and rapid; a 
thin film is formed on the surface at the end of thesecond day. Upon potato 
a brownish layer is formed at the end of twenty-four hours. In milk an 
acid reaction is produced. 
Pathogenesis.—Pathogenic for field mice, guinea-pigs, rabbits, and 
pigeons. The bacillus is found in the blood and various organs of infected 
mice, The spleen is found to be greatly enlarged. 
BACILLUS TYPHI MURIUM (LOffler). 
Obtained bv Léffler (1889) from mice which died in his laboratory from 
an epidemic disease due to this bacillus, 
Morphology.—Short bacilii, resembling the bacillus of diphtheria in 
pigeons, aa varying considerably in dimensions—like the bacillus of 
typhoid fever; grows out into flexible filaments. 
‘i Stains with the aniline colors—best with Loffler’s solution of methylene 
ue. 
Biological Characters.—An aérobic and facultative anaérobic, non- 
liquefying, motile bacillus. Spore formation not determined. Has flagella 
around the periphery of the cells, like those of the typhoid bacillus, and ex- 
hibits similar active movements. In gelatin stab cultures, at the room 
temperature, growth occurs upon the surface, at the end of forty-eight hours, 
in the form of a flat, grayish-white, round, semi-transparent mass the size of 
a pin’s head; later the surface colony increases in extent and has more or 
less irregular margins. In gelatin plate cultures the deep colonies are at 
first round. slightly granular, transparent, and grayish; later they are of a 
yellowish-brown color and decidedly granular. The superficial colonies are 
very granular and marked by delicate lines—similar to colonies of the 
typnoid bacillus. Upon agar a grayish-white layer is developed which is 
not at all characteristic. Upon potato arather thin, whitish layer isformed, 
and around. this the potato acquires a dirty bluish-gray color. In milk an 
abundant development occurs, and a decidedly acid reaction is produced 
without causing any perceptible change in the appearance of the fluid. 
Pathogenesis.—Pathogenic for white mice, which die in from one to two 
weeks after infection ; also to field mice, which succumb to subcutaneous in- 
jections of a pure culture, and also, in from eight to twelve days, when fed 
upon potato cultures or bread moistened with a small quantity of a bouillon 
culture. L6ffler believes that this bacillus may be used for the destruction 
of field mice in grain fields, inasmuch as they invariably die after ingesting 
food which has been contaminated with it, and also from eating the bodies 
