546 BACTERIOLOGY. 
bacilli in the animal body, and sometimes in cultures, 
are enclosed in a transparent capsule. 
Biological Characters. An anaérobic, non-motile, non- 
liquefying bacillus. Does not form spores. Grows at 
the room-temperature, but more rapidly at 37° C., in 
the usual culture media in the absence of oxygen, and 
is accompanied by the production of gas. Nutrient 
gelatin is not liquefied by the growth of this bacillus, 
but it is gradually peptonized. In agar colonies are 
developed which are from 1 to 2 mm. or more in 
diameter, grayish-white in color, and in the form of 
flattened spheres, ovals, or irregular masses, beset with 
hair-like projections. Bouillon is diffusely clouded, and 
a white sediment is formed. Milk is rapidly coagulated. 
Pathogenesis. Usually non-pathogenic in healthy 
animals, although Dunham found that the bacillus taken 
freshly from human infection is sometimes very virulent. 
When quantities up to 2.5c.¢. of fresh bouillon cultures 
are injected into the circulation of rabbits and the ani- 
mals killed shortly after the injection, the bacilli de- 
velop rapidly, with an abundant formation of gas in 
the bloodvessels and organs, especially the liver. The 
following is one of the best methods of obtaining 
the bacilli: The material suspected to contain the ba- 
cillus alone or associated with other bacteria is injected 
into rabbits, which are killed, kept at 37°C., and cultures 
made twenty-four hours later from their bodies. 
It is suggested by Welch that in some of the cases in 
which death has been attributed to the entrance of air 
into the veins the gas found at the autopsy may not 
have been atmospheric air, but may have been produced 
by this or some similar micro-organism entering the cir- 
culation and developing shortly before and after death. 
The bacillus has been found in the dust of hospitals. 
