Report on the Bacteriology of Water. 



173 



and in the sewage extensive multiplication of the organism actually 

 took place, as will be seen from the following table (see p. 174). 



If we endeavour to summarise the results obtained by these several 

 investigators, the evidence would appear to point to the following- 

 conclusions : — 



1. Spores of anthrax retain their vitality either in sterile or un- 



sterilised waters of the most varied character for long periods 

 of time, many months, at ordinary or low temperatures, whilst 

 they are slowly destroyed if the waters are kept at 35° C. 



2. The evidence concerning the sporeless anthrax bacilli is some- 



what contradictory. Most observers agree that they are 

 rapidly destroyed in a few days both in sterilised and un- 

 sterilised w r aters ; Straus and Dubarry, however, using a more 

 delicate method of cultivation, have found their vitality to be 

 retained for a much longer period, viz., from 28 to 65 days. 

 There can be little doubt that in these experiments spores were 

 formed in the waters. The results of Wolffhugel and Riedel 

 differ also- from those of other observers, probably owing to 

 their having added so much gelatine, inasmuch as they found 

 the anthrax bacilli to undergo abundant multiplication in 

 sterile waters at 16° and at 35° C, whilst rapid destruction 

 took place if the same waters were maintained at 7 — 10° C. 



3. As regards the power of anthrax to propagate in water, there is, 



with the exception of the last mentioned results of Wolffhugel 

 and Riedel, no evidence that they undergo multiplication in 

 ordinary potable waters even when sterilised ; indeed, it has 

 been clearly shown by one of us that no numerical increase 

 takes place either in sterile distilled or sterile filtered Thames 

 water. (Grand Junction Company), whilst in sterile London 

 sewage the numbers underwent very considerable multiplica- 

 tion. The power of propagation in sterile water at any rate 

 is, therefore, dependent on its chemical composition. It 

 should be mentioned that the multiplication observed by 

 Wolffhugel and Riedel was not in potable water proper, but in 

 the water of the River Panke at Berlin, which is, or was, 

 practically diluted sewage, although they also obtained multi- 

 plication when this water was diluted with ten times its 

 volume of distilled water. The whole question of multiplica- 

 tion, however, is doubtless to a large extent dependent on the 

 vigour of the anthrax growths employed for experiment. 



4. It is much to be regretted that so few investigators have made any 



experiments on the virulence of the anthrax organisms after 

 their residence in waters under varied conditions; this is, 

 after all, the chief point of practical importance, it is the point 



