PATHOGENIC BACTERIA. 27 1 



of a drum-stick. The spores are extremely resistant, and 

 in the dry condition can exist for years. They are killed 

 by moist heat at 100 C. in five minutes; by 5 per cent, 

 carbolic acid in fifteen hours ; by bichloride of mercury, 

 i-iooo, in three hours. The tetanus bacillus stains by 

 Gram's method. It is a strict anaerobe; it grows in an 

 atmosphere of hydrogen, but not of carbon dioxide. It may 

 sometimes be made to grow very well by Buchner's method. 



FIG. 69. 



tV 



Tetanus bacilli, showing spores. (X 1000.) 



It may be cultivated at the room temperature, but better in 

 the incubator. It grows upon ordinary culture-media, pref- 

 erably those containing dextrose. Gelatin is liquefied 

 slowly; the colonies in gelatin present characteristic radi- 

 ating filaments and look like a thistle. It grows on the 

 other culture-media. Gas formation is not pronounced. 



This organism appears to be widely spread in external 

 nature, especially in the soil. It is often found in garden 

 earth, and in the feces of herbivorous animals. McFarland 



