256 



Profs. Percy Frankland and Marshall Ward. 



The results seem to show conclusively that the maximum number is 

 not only higher at the higher temperature, but that it is attained more 

 rapidly. That this is, at least in part, due to the bacteria being enabled 

 to multiply and diffuse themselves through the liquid more rapidly, 

 before the available oxygeu and food materials are diminished, seems 

 an obvious conclusion ; though I do not believe that these factors 

 alone explain the phenomenon. 



Experiments with the Vegetative Bacilli of Anthrax in Thames Water. 



It is necessary to know, if possible, whether the living vegetative 

 bacilli of anthrax can survive immersion in such waters as we have 

 experimented with, and then to see if they can multiply therein : 

 that spores can withstand such immersion has long been known, and 

 we gave very full particulars on this point in our First Report,* but 

 the evidence regarding the vegetative bacilli is somewhat conflicting, 

 and consequently I have devoted attention especially to this point. 

 The difficulties are decidedly great. In the first place it is not easy 

 to obtain spore-free bacilli, and it will be objected that in some of the 

 following cases it is not certain that my material was absolutely spore- 

 free ; this cannot be gainsaid, but it can at least be claimed from the 

 experiments that, while they do not absolutely settle the question 

 whether the vegetative bacilli can or cannot multiply in Thames 

 water, they do show that, if such bacilli obtain access to the water 

 and form spores in it, they are very tenacious of life and difficult to 

 exterminate. 



Preliminary . 



On January 28, 1892, a sterilised J-litre flask was charged with 

 25 c.c. of Thames water, fresh from the river, and inoculated with a 

 large charge of a potato cultivation of a normal anthrax grown at 

 16° C, and devoid of spores, so far as could be ascertained. We 

 employed a potato culture in order to introduce as little nitrogenous 

 food material as possible into the water, and chose a tube grown at a 

 relatively low temperature (16° C.) to try and prevent the precocious 

 development of spores. 



Five J- litre flasks were then charged each with 25 c.c. of the 

 freshly-collected Thames water, and inoculated each with 1 c.c. of the 

 above infecting fluid. The flasks were marked A, B, C, D, and E. 



Flask A was selected for periodic examination, to obtain a pre- 

 liminary answer to the question, Can Bacillus anthracis maintain 

 itself alive at all in Thames water ? Pipettes were selected to 

 drop 25 drops to the 1 c.c. 



After standing 24 hours at 20° C, we made a series of plates (on 



* See ' Roy. Soc. Proc.,' vol. 51, 1892, pp. 219 and 268. 



