210 Profs. P. F. Frankland and Marshall Ward. 



water, for by tlie process of filtration the number of different 

 varieties of micro-organisms is largely reduced, as is at once seen by 

 the inspection of the plate cultivations, and those varieties which 

 remain have, therefore, a more favourable opportunity for reproduc- 

 tion than in the presence of more numerous varieties.* 



The specific forms experimented with were the Bacillus pyocyaneus 

 (from green pus), Finkler- Prior's Spirillum, and Koch's Spirillum of 

 Asiatic cholera; they were in all cases introduced into sterilised waters 

 only. 



The Bacillus pyocyaneus was found to multiply extensively in distilled 

 water, filtered Thames water, deep-well water, and London sewage. 

 Finkler-Prior's Spirillum, on the other hand, exhibited a most extra- 

 ordinary susceptibility to immersion in water, for in none of these 

 waters could its presence be demonstrated after the first day. 



The results obtained with Koch's Spirillum of Asiatic cholera were 

 particularly instructive, for when this was taken from a weak culture 

 in gelatine, the spirilla were no longer demonstrable after the first 

 day in the infected waters, but when the spirilla of the same cultiva- 

 tion were revivified by cultivation in broth and then introduced into 

 the aqueous media they were found to multiply abundantly in the 

 sewage, whilst in the deep-well and filtered Thames water they 

 underwent numerical reduction in the first instance, followed by 

 slight multiplication, which was again succeeded by decline, and on 

 the ninth day they were still demonstrable. A temperature of 35° C. 

 caused their more rapid destruction, as confirmed by the results of 

 other investigators. 



In a later paper by one of usf the author finds that the cholera 

 spirilla have remained alive for eleven months in the sterile sewage, 

 and in further experiments with Bacillus anthracis, he found that in 

 sterile distilled and in sterile filtered Thames water the organisms 

 remained alive for upwards of sixty days, a considerable diminution 

 taking place during the first days, after which the numbers remained 

 practically constant. The initial diminution, he suggests, is due to 

 the dying off of the bacilli, the spores alone surviving. In sterile 

 London sewage Bacillus anthracis underwent considerable multiplica- 

 tion. Experiments were also made with the Streptococcus of erysi- 

 pelas (Fehleisen), which was apparently destroyed within one hour 

 in distilled water, but lived from two to five days in sterile filtered 

 Thames water, and two days in sterile London sewage. 



* These results are partly in accordance with, and partly contradictory of, 

 Miquel's observation that the action of numerous Schizomycetes in a -water may 

 render that water " immune " to infection by other Schizomycetes, as quoted in 

 the footnote to p. 203. 



t Percy F. FranEand, "Recent Bacteriological Research in connection with 

 Water Supply," ' Journ. Soc. Chem. Industry,' 1887. 



