CHAPTER VII. 



BACILLUS OF TETANUS. 



Bacillus tetani, or the bacillus of Nicolaier, is the exciting 

 cause of tetanus. It was first obtained in pure culture by 

 Kitasato, in 1889, but was discovered by Nicolaier as early 

 as 1884. It is the accepted cause of tetanus. It is found in 

 the purulent discharge of tetanus, at the site of inoculation ; 

 in the soil, especially garden earth ; and in the excretions of 

 horses and cattle. Its appearance is very characteristic. 



Biology and morphology : It is a very slender germ, about 

 the size of a small red blood-corpuscle, from 3 to 5 p. in length, 



FIG. 93. 



Tetanus bacilli with spores in distended ends. X 1100. (Park.) 



with an enlargement at one end containing a spore, the typical 

 drum-stick shape (Fig. 93). When the bacterium is not sporu- 

 lating, its ends are rounded and it is regular in outline. It 

 has no flagella, but is motile nevertheless. It usually occurs 

 singly, rarely forming chains. It is an obligative anaerobe, 

 and will not grow in the presence of the slightest amount of 



