NOT DESCRIBED IN PREVIOUS SECTIONS. 537 
difference in their colony growth on gelatin, and in gelatin stab cultures 
bacillus B does not show the nail-form growth with marked end swelling in 
the depth. In potato cultures the Bacillus lactis aérogenes shows a differ- 
ence between old and new potatoes, while bacillus B does not show any 
difference. 
‘* Bacillus B possesses decided pathogenic properties, which was shown 
both by hypodermic injections and feeding with milk cultures.” 
BACILLUS ACIDIFORMANS. 
Obtained by the writer (1888) from a fragment of yellow-fever liver pre- 
served for forty-eight hours in an antiseptic wrapping; since obtained from 
Fig. 148. Fig, 149, 
Fie. 148.—Bacillus acidiformans, from a potato culture. x 1,000. From wu photomicrograph 
(Sternberg ) 
Fia. 149.—Culture of Bacillus acidiformans in nutrient gelatin, end of four days at 22° C. 
From a photograph. (Sternberg.) 
liver preserved in the same way from two comparative autopsies—i.e., not 
cases of yellow fever. 
Morphology.—A. short bacillus with rounded corners, sometimes short. 
oval in form; from 14 to 3 # in length and about 1.2 u in breadth; may grow 
out into filaments of 5 to 10 ~, or more, in length; in some cultures the short. 
oval form predominates. 
Stains readily with the aniline colors usually employed, and by Gram’s 
method. 
Biological Characters.—An aérobic and facultative anaérobic, non- 
liquefying, non-motile bacillus. Does not form spores. Grows rapidly at 
the room temperature in the usual culture media. Grows in decidedly acid 
media; in culture media containing glycerin or glucose it produces an abun- 
dant evolution of carbon dioxide, and a volatile acid is formed. 
It does not liquefy gelatin, and in stab cultures grows abundantly both 
on the surface and along the line of puncture. At the end of twenty-four 
hours, at 22°C., a moniled white mass is formed upon the surface, resembling 
the growth of Friedlander’s bacillus; at the bottom of the line of puncture 
the separate colonies are spherical, opaque, and pearl-like by reflected light. 
Gas bubbles are formed in the gelatin. At the end of a week thesurface is 
covered with a thick, white, semi-fluid mass. _ 
In gelatin roll tubes the superticial colonies are translucent or opaque, 
and circular or somewhat irregular in outline; by reflected light they are 
