386 Tetanus 



Morphology. The tetanus bacillus is a long, slender 

 organism measuring 0.3 to 0.5 X 2 to 4^ (Fliigge). Its most 

 striking characteristic is an enlargement of one end, which 

 contains a large round spore. The bacilli in which no 

 spores are yet formed have rounded ends and seldom unite 

 in chains or pairs. They are motile and have many flagella 

 arising from all parts of the surface (petrichia). 



Staining. The bacilli stain readily with ordinary aqueous 

 solutions of the anilin dyes and by Gram's method. 



Fig. 117. Bacillus tetani. X 1000 (Frankel and Pfeiffer). 



Isolation. The method usually employed for the isolation 

 of the tetanus bacillus was originated by Kitasato, and based 

 upon the observation that its spores can resist exposure to 

 high temperatures for considerable periods of time. After 

 finding by microscopic examination that the bacilli were 

 present in pus, Kitasato spread it upon the surface of an 

 ordinary agar-agar tube and incubated it for twenty-four 

 hours, during which time all of the contained micro-organ- 

 isms, including the tetanus bacillus, increased in number. 

 He then exposed it for an hour to a temperature of 80 C., 

 by which all fully developed bacteria, tetanus as well as the 

 others, and the great majority of the spores, were destroyed. 

 As scarcely anything but the tetanus spores remained alive, 

 their subsequent growth gave a fairly pure culture. 



Cultivation. The tetanus bacillus is difficult to culti- 



