Report on the Bacteriology of Water. 



209 



resistant to the water bacteria among which they find them- 

 selves. 



In distilled water the cholera spirilla usually died off rapidly,* bnt 

 cases happened where they lived for thirty-three days ; possibly the 

 distilled water contained impurities in these cases. 



The authors insist on the danger of cholera germs in water, and 

 expecially in ordinary river, well, and tap waters, which showed the 

 presence of living cholera germs seven months after infection. 



In the paper by one of usj the particular waters submitted 

 to examination were those of the rivers Thames and Lea before and 

 after filtration by the several London Companies, as well as the deep- 

 well water from the chalk supplied by the Kent Company. It was 

 found that the microbes in the unfiltered waters underwent but little 

 multiplication, and in some cases very considerable diminution, on 

 standing at the ordinary temperature of the air, whilst at a tempera- 

 ture of 35° C. very rapid multiplication took place, which was followed 

 by subsequent decline. In the case of the filtered river waters, on 

 the other hand, there was invariably a large increase, especially at the 

 high temperature, also followed, however, by a subsequent decline. 

 By far the most rapid multiplication was observed in the case of the 

 organically pure deep- well water; thus on one occasion the numbers 

 rose from 7 to 495,000 in the course of three days when the water 

 was kept at 20° C. ; the tendency to a subsequent decline was, how- 

 ever, also exhibited. On these surprising results the author points 

 out that the deep- well w^ater is at the outset almost wholly free from 

 micro-organisms, and that it has never before been inhabited by such 

 living matters, and that it is only reasonable to infer, therefore, that 

 those of its ingredients which are capable of nourishing the particular 

 micro-organisms which flourish in it are wholly untouched, whilst in 

 the case of the river waters, the most available food supply must have 

 been largely explored by the numerous generations of micro-organ- 

 isms which have inhabited them. Further, he remarks that the 

 number of different varieties of micro-organisms is far greater in the 

 case of the river waters than in that of the deep- well water, and that 

 in the latter case, therefore, the organisms present will probably have 

 a freer field for multiplication than in the presence of competitors, 

 some of which may not improbably give rise to products which are 

 hostile to others. 



In a similar manner he explains the greater capacity for multipli- 

 cation exhibited by the filtered as compared with the unfiltered river 



* As the authors point out, this agrees with Babes' results (Virchow's ' Arch. f. 

 Path. Anat.,' vol. 99, 1885, p. 152), and contradicts those of Mcati and Eietsch 

 (' Revue d'FTyg.,' 1885, No. 5, p. 353). Since the latter employed liquid cultures 

 of the bacilli, they probably introduced food materials into the water. 



f Loc. cit., p. 471. 



