PATHOGENIC BACTERIA IN DIFFERENT WATERS 313 



On systematically examining these several tubes, it was 

 found that on the fifth day, whereas anthrax was no 

 longer discoverable in the tubes kept at 5 C., it was pre- 

 sent in large numbers in those kept at 19 C., whilst in 

 those which had been preserved at 13 C. it was still 

 present, although in diminished numbers. Again, after 

 fourteen days, all the tubes kept both at 5 C. and at 

 13 C. were found quite free from anthrax, whilst the 

 tubes maintained at 19 C. yielded large numbers of 

 anthrax colonies. That the anthrax in these latter 

 tubes was present in the spore form was proved by 

 the fact that they resisted heating to 70 C. for ten 

 minutes. 



These results clearly show that the anthrax bacilli 

 underwent destruction in the course of a few days in 

 the sterile Thames water which was kept at tempera- 

 tures below that at which spore-formation can take 

 place ; whilst on the other hand the bacilli from the 

 same source, in the same water, maintained at 19 C., 

 gave rise to an abundant crop of spores, the vitality of 

 which was indefinitely preserved. The precise tem- 

 perature at which anthrax bacilli form spores possibly 

 varies to some extent according to their origin and 

 previous history, for in Meade Bolton's experiments, 

 recorded in the table above, it appears that no spores 

 can have been formed, although the water is said to 

 have been preserved at 20 C. 



What may be the behaviour in water of that variety 

 of anthrax known as asporogene, and which is incapable 

 of forming spores under any known conditions, has not 

 yet been determined. 



