CHAPTER XXIII 



PATHOGENIC ANAEROBIC BACILLI 



B. Tetani. The association of tetanus with wounds and soil 

 was early recognized, but for centuries all attempts to find the excit- 

 ing cause failed. In 1884 Nicolaier succeeded in infecting mice 

 and rabbits by inoculating them with garden soil, but by none of 



the ordinary methods was he 

 able to isolate an organism 

 which would give rise to the 

 disease. In 1889 Kitasato suc- 

 ceeded in isolating from lesions 

 in mice which had been inocu- 

 lated with material from a 

 human case a bacillus which 

 when injected in pure cultures 

 into animals produced the 

 characteristic symptoms. He 

 further demonstrated that the 

 cause of the earlier failures to 

 obtain the organism was due to the fact that it could only grow 

 alone in the absence of oxygen. 



Morphology and Staining. The tetanus bacilli appear as 

 slender rods with rounded ends about 4 /* in length and 0.4 p 

 in diameter. They readily form spores which are round and have 

 a diameter usually much larger than the thickness of the bacilli ; 

 the spore develops at one end of the organism, giving it an appear- 

 ance somewhat like a drumstick (Fig. 33). The bacilli are 

 slightly motile in the vegetative form and possess a large number 

 of peritrichal flagella. They stain with the ordinary anilin dyes 

 and are not decolorized by Gram's method. 



242 



FIG. 33. Tetanus Bacilli. 



