410 BACTERIOLOGY. 



single colonies appear as discrete globules that cause 

 rapid liquefaction of the gelatin and ultimately coalesce 

 into irregular, lobulated, liquid areas. In some of the 

 larger colonies an ill-defined, concentric arrangement of 

 alternate clear and cloudy zones can be made out. 

 (Fig. 90.) 



In deep-stab cultures in gelatin, growth begins after 

 about two or three days' at 20 to 25 C. It begins 

 usually at .about one or two centimetres below the sur- 

 face and causes slow liquefaction at and around the track 

 of its development. During the course of its growth 

 gas-bubbles are produced. 



In deep-stab cultures in agar-agar at 37 to 38 C. 

 growth begins in from twenty-four to forty-eight hours, 

 also at about one or two centimetres below the surface, 

 and is accompanied by the production of gas-bubbles. 

 There is produced at the same time a peculiar, penetrat- 

 ing odor somewhat suggestive of that of rancid butter. 

 Under these conditions spores are formed after about 

 thirty hours. 



It grows well in bouillon of very slightly acid reac- 

 tion under hydrogen, but does not retain its virulence 

 for so long a time as when cultivated upon solid media. 

 In this medium it develops in the form of white floc- 

 culi that sink ultimately to the bottom of the glass and 

 leave the supernatant fluid quite clear. If the vessel be 

 now gently shaken these delicate flakes are distributed 

 homogeneously through it. In bouillon cultures there 

 is often seen a delicate ring of gas-bubbles around the 

 point of contact of the tube and the surface of the 

 bouillon. There is produced also a peculiar penetrating 

 sour or rancid odor. 



It grows best at the body temperature, i. e., from 37 



