THE BACILLUS OF TETANUS. 387 
Its growth in the animal organism is comparatively 
seanty, 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, anaérobic 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 up 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 anaérobes. 
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 
