TEANSACTIONS OF SECTION D. 



703 



On storage in sterilised vessels at 20° C, however, a great change in the rela- 

 tionship of these numbers soon takes place, for whilst the number of organisms in 

 the crude river-water undergoes but little change or even suifers diminution, that 

 in the filtered river-water exhibits very rapid multiplication, and this increase is 

 even still more marked in the case of the deep-weU water. The author suggests 

 that the ditferences in the rate of multiplication exhibited by these three kinds of 

 water is dependent upon the number of different varieties of micro-organisms which 

 they contain. Thus in the unfiltered river-waters the organisms belong to a number 

 of different kinds ; the filtered river-waters exhibit fewer varieties ; whilst in the 

 deep-well water the number of varieties is still more limited, the gelatine-plates 

 having generally the appearance of almost pure cultivations. The microbes in the 

 deep-well water will thus be less hampered in their multiplication by hostile com- 

 petitors than those in the filtered river-waters, and these again less than those in 

 the crude river-waters, in which an equilibrium must have already been established 

 between the various competitors. 



When the waters were exposed to a temperature of 35° C. the multiplication 

 was in all cases very much more rapid, but both at 20° 0. as well as at 35° C. the 

 multipUcation was, on prolonged storage, followed by reduction. 



The pathogenic forms which have been studied by the author are (1) Koch's 

 ' Cotnma ' spirillum of Asiatic cholera, (2) Finkler-Prior'a ' Comma ' spirillum of 

 European cholera, and (3) the Bacillits pyocyaneus, which produces the greenish- 

 blue colouring-matter frequently present in abscesses. The vitality of these 

 organisms has been studied by introducing minute quantities of their cultivations 

 into sterilised distilled water, deep-well water, filtered Thames water, and London 

 sewage. In these media they present some very striking differences. Thus the 

 Bacillus pyocyaneus was found to flourish in all ; even in distilled water it was 

 present in largely midtiplied numbers after fifty-three days. Koch's ' Comma ' 

 spirOlum, on the other hand, when introduced into deep-well water was no longer 

 demonstrable after the ninth day, whilst in sewage it was still found in enormously 

 multiplied numbers after twenty-nine days. 



Finkler-Prior's ' Comma ' spirillum, although showing such far greater vital 

 activity than Koch's in gelatine cultures, possesses far less vitality than the latter 

 when introduced into water. Thus in the above-mentioned media it was in no 

 case demonstrable after the first day. 



A curious phenomenon was observed in the case of the Bacillus pyocyaneus and 

 Koch's ' Comma ' spirillum, viz. that when introduced into water a large propor- 

 tion of these organisms at first perish, the numbers often becoming greatly reduced, 

 the survivors subsequently, having apparently adapted themselves to the new 

 medium, multiplying to a greater or less extent. 



The author points out how necessary it is that each pathogenic organism should 

 be made the subject of separate investigation, and how fallacious must be any 

 generalisations concerning the vitaUty of pathogenic microbes which are based upon 

 the study of a single form. 



The more important results referred to above are summarised in the following 

 table : — 



Bacillus Pyocyaneus in Distilled, Deep Well, Filtered Thames 



Water, and Sewage. 



