THE BACILLUS OF TETANUS. 387 



Its growth in the animal organism is comparatively 

 scanty, and is usually associated with other bacteria; 

 hence, it is difficult to obtain it in pure culture. The 

 method of procedure proposed by Kitasato, which, how- 

 ever, is not always successful, consists in inoculating an 

 agar tube with the tetanus-bearing material (pus from 

 the inoculation wound), keeping this for twenty-four to 

 forty-eight hours at a temperature of 37 C., and, after 

 the tetanus spores have formed, heating it for about an 

 hour at 80 C., to destroy the associated bacteria. The 

 spores of the tetanus bacillus being able to survive this 

 exposure, anaerobic cultures are then made in the usual 

 way, and the tetanus colonies thus isolated. The fur- 

 ther development is unattended with difficulty. On 

 gelatin plates the colonies develop slowly; they resemble 

 somewhat the colonies of the bacillus subtilis, and have 

 a dense, opaque centre surrounded by fine, diverging 

 rays. Liquefaction takes place more slowly, however, 

 than with the bacillus subtilis, and the resemblance to 

 these colonies is soon lost. In old cultures the entire 

 mass is made iip of a number of fine threads, and the 

 colonies are not unlike those of the common mould. 



The colonies on agar are quite characteristic (San- 

 felice). To the naked eye they present the appearance 

 of light, fleecy clouds; under the microscope, a tangle 

 of fine threads. The extreme fineness of the threads 

 enables them to be distinguished from the colonies of 

 -other anaerobes. 



The stab cultures in gelatin exhibit the appearance of 

 a cloudy, linear mass, with prolongations radiating into 

 the gelatin from all sides. Liquefaction takes place 

 slowly, generally with the production of gas. In stab 

 cultures in agar a growth occurs not unlike in structure 



