TETANUS. 



147 



FIG. 61. 



20 C., but best at 37 C. It does not grow at a tempera- 

 ture below 14 C. Cultures must be kept in a hydrogen 

 atmosphere, as the presence of the oxy- 

 gen of the air prevents their growth. 



On the surface of gelatin the cultures 

 resemble very much those of the Ba- 

 cillus subtilisy but liquefy the medium 

 more slowly (Fig. 61). 



In gelatin stab-cultures it grows in 

 the depth of the medium, and the col- 

 onies have very much the appearance 

 of a fir tree. Its growth is very slow 

 in this medium, but the addition of 

 from 1 to 2 per cent, of glucose to the 

 gelatin increases materially the rapidity 

 of the growth. The growth on agar is 

 very much like that on gelatin, but it 

 causes no liquefaction of the medium. 



In bouillon it grows at 37 C., in the 

 depth of the tube, with the production 

 of gases. It does not cause coagula- 

 tion of milk, and produces no acids in 

 its cultures. All cultures of it are noted 

 for their characteristic disagreeable odor. 



To obtain pure cultures of the Bacillus 

 tetani, a number of methods have been 

 resorted to ; that recommended by Kit- 

 asato is as follows : 



The pus or secretion of the wound in 

 a case of tetanus, or some garden or 

 stable soil containing the sporing form 

 of Bacillus tetani, is plated on agar, or 

 streak cultures are made on this me- 

 dium with the secretions of the wound 

 or with the contaminated soil. These 

 agar plates or tubes are kept at the 

 temperature of the incubator for three or four days, so as 

 to allow the growth of all bacteria contained therein. At 



Colonies of the tetanus 

 bacillus four days old, made 

 by distributing the organ- 

 isms through a tube nearly 

 filled with glucose-gelatin. 

 Cultivation in an atmos- 

 phere of hydrogen. (From 

 Fraenkel and Pfeiffer.) 



