382 



TETANUS. 



tetanus spores which can develop in pure culture. Another 

 variation may be adopted by making use of Vignal's method 

 (p. 70) at any stage of the procedure just described. The 

 isolation of the tetanus bacillus is in many cases a difficult 

 matter, and various expedients require to 

 be tried. 



Characters of Cultures. Pure cul- 

 tures having been obtained, subcultures 

 can be made in deep upright glucose 

 gelatine or agar tubes. On glucose gela- 

 tine in such a tube there commences, 

 an inch or so below the surface, a 

 growth consisting of fine straight threads, 

 rather longer in the lower than in the 

 upper parts of the tube, radiating out 

 from the needle track (Fig. 99). Slow 

 liquefaction of the gelatine takes place, 

 with slight gas formation. In agar the 

 growth is somewhat similar, consisting of 

 small nodules along the needle track, 

 with irregular short off-shoots passing out 

 into the medium (Fig. 102, A). There is 

 slight formation of gas, but, of course, no 

 liquefaction. Growth also occurs in 

 blood serum and also in glucose bouillon 

 under anaerobic conditions. The latter 

 is the medium usually employed for 

 obtaining the soluble products of the 

 organism. There is in it at first a slight 

 bacillus in glucose turbidity, and later a thin layer of a 

 gelatine, showing the powdery deposit on the walls of the 



ItoT ; vessel A11 the cultures S- e out a 

 peculiar burnt odour of rather un- 

 pleasant character. 



Conditions of Growth, etc. The B. tetani grows best at 

 37 C. The minimum growth temperature is about 14 C., 

 and below 22 C. growth takes place very slowly. Growth 

 takes place only in the absence of oxygen, the organism 



FIG. 99. Stab 

 culture of the tetanus 



