342 Tetanus 



twenty-four hours, during which time all of the contained micro- 

 organisms, including the tetanus bacillus, increased in number. 

 He then exposed it for an hour to a temperature of 8oC., by which 

 all fully developed bacteria, tetanus as well as the others, and the 

 great majority of the spores, were destroyed. As scarcely anything 

 but the tetanus spores remained alive, their subsequent growth 

 gave a fairly pure culture. 



Cultivation. The tetanus bacillus is difficult to cultivate because 

 it will not grow where the smallest amount of free oxygen is present. 

 It is hence a typical obligatory anaerobe. Farran* and Grixoni 



Fig. 125. Bacillus tetani; five-day-old colony upon gelatin containing glucose. 

 X 1000 (Frankel and Pfeiffer). 



believe it to have originally been an optional anaerobe, and it is said 

 by these writers that the organism can gradually be accustomed to 

 oxygen so as to grow in its presence. When this is achieved, it loses 

 its virulence. 



The general methods for the cultivation of anaerobic organisms, 

 are given under the appropriate heading (Anaerobic Cultures), and 

 need not be repeated here. 



The colonies of the tetanus bacillus, when grown upon gelatin 

 plates in an atmosphere of hydrogen, resemble those of the well- 

 known hay bacillus. There is a rather dense, opaque central mass 

 surrounded by a more transparent zone, the margins of which con- 

 sist of a fringe of radially projecting bacilli. Liquefaction occurs 

 slowly. 



* "Centralbl. f. Bakt. u. Parasitenk.." July 15, 1898, p. 28. 



