I7O BACTERIA 



forms predominate, particularly so in old cultures. Clubbed 

 forms, not unlike the bacillus of diphtheria, may often be 

 seen from agar cultures. Without doubt the most peculiar 

 characteristic of this bacillus is its sporulation. The well- 

 formed round spores occur readily at incubation temperature. 

 They occupy a position at one or other pole of the bacillus, 

 and have a diameter considerably greater than the rod. 

 Thus the well-known " drumstick " form is produced. In 

 practice the spores occur freely in the medium and in micro- 



" 1 V' 



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BACILLUS OF TETANUS 



scopical preparation. Like other spores, they are extremely 

 resistant to heat, desiccation, and antiseptics. They can 

 resist boiling for several minutes. 



As we have seen, this bacillus is a strict anaerobe, grow- 

 ing only in the absence of oxygen. The favourable temper- 

 ature is 37 C. , and it will only grow very slowly at or below 

 room temperature. 



An excellent culture is generally obtainable in glucose 

 gelatine. The growth occurs, of course, only in the depth 

 of the medium, and appears as fine threads passing horizon- 

 tally outwards from the track of the needle. At the top 

 and bottom of the growth these fibrils are shorter than at 

 the middle or somewhat below the middle. For extraction 

 of the soluble products of the bacillus glucose broth may be 

 used. 



