236 



PATHOGENIC BACTERIA. 



in manure, and sometimes in the intestinal discharges 

 of animals. It is extremely difficult to isolate and culti- 

 vate, because it will not grow where the smallest amount 

 of oxygen is present. 



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- 



FiG. 67. Bacillus tetani : six-days- FIG. 68. Bacillus tetani : culture 

 old puncture-culture in glucose-gelatin four days old in glucose-gelatin (Fran- 

 (Frankel and Pfeiffer). kel and Pfeiffer). 



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 80 C. By this heating all the fully- 

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



