448 



BAGTEBIOLOQY. 



Fig. 97. 



It forms spores, and when in this stage is seen to be 

 slightly swollen at or near one of its poles, the location in 

 which the spore usually appears. (Fig. 

 96, B.) It is conspicuously prone to un- 

 dergo degenerative changes, and involu- 

 tion-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 loses this property and 

 becomes motionless when spores are form- 

 ing. 



It is strictly anaerobic and cannot be 

 cultivated in an atmosphere in which oxy- 

 gen is present. It grows best under hy- 

 drogen, and does not grow under carbonic 

 acid. 



The media most favorable to its growth 

 are those containing glucose (1.5 to 2 per 

 cent. ), glycerin (4 to 5 per cent. ), or some 

 other reducing body, such as indigo-so- 

 dium sulphate, sodium formate, etc. 



When cultivated upon gelatin plates 

 in an atmosphere of hydrogen the col- 

 onies appear as irregular, slightly lobu- 

 lated masses. After a short time lique- 

 faction of the gelatin occurs and the 

 culture. (After colony presents a dark, dense, lob ulated 



FRANKELand iii , iii 



pfeiffer.) ^^d broken centre, surrounded by a 



much more delicate, fringe-like zone. 



When distributed through a deep layer of liquefied 



gelatin that is subsequently caused to solidify colonies 



develop at only the lower portions of the tube. The 





I 



Colonies of the 

 bacillus of symp- 

 tomatic anthrax, 

 in deep gelatin 



