5 30 BA CTERIOL OGY. 



It is markedly prone to undergo degenerative changes, 

 and involution-forms are commonly seen not only in fresh 

 cultures, but in the tissues of affected animals as well. 



Though actively motile when in the vegetative stage, it, 

 like all other motile spore-forming bacilli, loses this prop- 

 erty and becomes motionless when spores are forming. 



It is strictly anaerobic and cannot be cultivated in an at- 

 mosphere in which free oxygen is present. It grows best 

 under hydrogen, and does not grow under carbonic acid. 



The media most favorable to its growth are those con- 

 taining glucose (1.5 to 2 per cent.), glycerin (4 to 5 per 

 cent.), or some other reducing-body, such as indigo- 

 sodium sulphate, sodium formate, etc. 



When cultivated upon gelatin plates in an atmosphere 

 of hydrogen the colonies appear as irregular, slightly 

 lobulated masses. After a short time liquefaction of the 

 gelatin occurs and the colony presents a dark, dense, 

 lobulated and broken centre, surrounded by a much more 

 delicate, fringe-like zone. 



When distributed through a deep layer of liquefied 

 gelatin that is subsequently solidified colonies develop 

 at only the lower portions of the tube. The 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. 92.) 



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 



