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 aerogenes 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. 



Fro. 148. Bacillus aciiiformans, from a potato culture, x 1,000. From a photomicrograph* 

 (Sternberg ) 



Fio. 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 1| to 3 fJ- 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 aerobic and facultative anaerobic, 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 rounded 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 the surface is 

 covered with a thick, white, semi-fluid mass. 



In gelatin roll tubes the superficial colonies are translucent or opaque, 

 and circular or somewhat irregular in outline; by reflected light they are 



