232 CLINICAL BACTERIOLOGY. 



nonmotile. The diameter of the spores measures from i to i . 5 /*. 

 They are extremely resistant to the action of heat. They are 

 not injured by exposure for an hour to a temperature of 8o p C. 

 (176 F.), and they are not destroyed by live steam with a 

 temperature of 100 C. (212 F. ) before the lapse of five or 

 eight minutes. The spores are also rather resistant to chemic 

 disinfectants. They are not destroyed in five per cent, carbolic 

 acid before the lapse of fifteen hours ; and they die in one per 

 cent, solution of mercuric chlorid within three hours. 



Staining. The tetanus-bacilli stain readily with the usual 

 dyes, and they can be stained also by Gram's method. The 

 spores can be demonstrated by the usual methods for staining 

 spores. 



Pure Cultures. The tetanus-bacillus is encountered in 

 nature (garden-soil, dust, animal excrement) and also in the 

 pus from wounds infected with tetanus always in association 

 with numerous other bacteria, some of which are anaerobic and 

 others aerobic. On account of the difficulty of isolating the 

 tetanus-bacillus from its associates, the attempt to obtain it in 

 pure culture long failed. Kitasato overcame this difficulty by 

 availing himself of the great resistance of the tetanus-spores. 

 He inoculated tetanus-pus upon agar-tubes ; after exposure for 

 two days in the thermostat, in addition to the other bacteria 

 there were found also numerous characteristic bristle-like rods 

 with bulbous heads. The mixed culture was now heated in the 

 water-bath at temperature of 80 C. (176 F. ) for an hour, 

 when all of the bacteria, including the tetanus-bacilli, were de- 

 stroyed, and only the tetanus-spores survived. These could 

 now be grown in pure culture without difficulty by the various 

 culture-methods employed for other anaerobic bacteria. It 

 ought, however, not occasion surprise if a pure culture should 

 not succeed even by this method, if, as happens rarely, other 

 resistant spores are present in the material submitted to exam- 

 ination. Under these circumstances anaerobic plates must be 

 made, by means of which, further, it is possible to isolate the 

 tetanus-bacilli in the discharge (pus). 



Cultural Properties of the Tetanus-bacillus. The 

 tetanus-bacillus grows upon all the customary culture-media 

 with exclusion of oxygen, and to which grape-sugar (two per 

 cent.) may be advantageously added. All tetanus-cultures pos- 

 sess in common a peculiar, rather disagreeable odor of burned 

 material. 



On gelatin-plates at room-temperature there appear about on 

 the fifth day, slowly growing, small colonies, with radiate pro- 

 cesses that give to the whole a feathery or thistle-like appear- 

 ance. Microscopic examination discloses in the center a dense, 

 yellowish mass, with numerous delicate, ciliary fibers and pro- 



