376 



TETANUS 



killed, except the tetanus spores which can develop in pure 

 culture. 



(3) Some method of anaerobically making plates, such as 

 that of Bulloch, may be employed. The isolation of the tetanus 

 bacillus is in many cases a difficult matter, 

 and various expedients require to be tried. 



Characters of Cultures. Pure cultures 

 having been obtained, sub-cultures can be 

 made in deep upright glucose gelatin or 

 agar tubes. On glucose gelatin 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. 128). Slow 

 liquefaction of the gelatin takes place, with 

 slight gas formation. In agar the growth is 

 somewhat similar, consisting of small nodules 

 along the needle track, with irregular short 

 offshoots passing out into the medium (Fig. 

 131, 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 or- 

 ganism. There is in it at first a slight 

 turbidity, and later a thin layer of a 

 powdery deposit on the walls of the vessel. 

 FIG. 128 -Stab cul- A ] 1 ^e cultures give out a peculiar burnt 

 ture of the tetanus odour of rather unpleasant character, 

 bacillus in glucose Conditions of Growth, etc. The b. 

 gelatin, showing tetani grows best at 37 C. The minimum 

 the lateral shoots growt h temperature is about 14 C., and 

 (Kitasato). .Natural , -, ^,^0 ^ ^1^1 i i i 



g ize below 22 C. growth takes place very slowly. 



Growth takes place only in the absence of 

 oxygen, the organism being a strict anaerobe. Sporulation may 

 commence at the end of twenty-four hours in cultures grown 

 at 37 C., much later at lower temperatures. Like other 

 spores, those of tetanus are extremely resistant. They can 

 usually withstand boiling for five minutes, and cAn be kept in 

 a dry condition for many months without being killed or losing 

 their virulence. They have also high powers of resistance to 

 antiseptics. 



