TETANUS. 



373 



an optional anaerobe, originally an aerobic organism. 

 When trained to grow in the presence of oxygen it loses 

 its virulence. 



The method now generally employed for the isolation 

 of this bacillus is that originated by Kitasato, and based 

 upon his observation that its spores can resist high temper- 

 atures. After finding that the typical bacilli are present 

 in earth or pus, or whatever the material to be investi- 

 gated was, Kitasato exposed a portion of it for an hour 

 to a temperature of 8o° C. By this heating all the fully- 

 developed bacteria, tetanus as well as the others, and the 



Fig. 82. — Bacillus tetani : five-days-old colony upon gelatin containing glucose ; 

 x 1000 (Fiankel and Pfeiffer). 



great majority of the spores except those of tetanus, were 

 destroyed, and, as little other than tetanus spores re- 

 mained, their cultivation was made comparatively easy. 

 The resistance which the tetanus bacilli manifest toward 

 heat is only part of a great general resisting power of 

 which they are possessed. It is said that they can retain 

 their vitality in the dried condition for months. Stern- 

 berg says they can resist 5 per cent, carbolic solutions 



