240 MICRO-ORGANISMS IN WATER 



sample fourteen days old had ninety-two. In the case 

 of samples preserved for a long time (206 days) the 

 bacterial contents were found to be as variable as in 

 the case of freshly prepared samples, the difference 

 ranging between one or two and over 100,000 ; but 

 taking the experiments as a whole, it was ascertained 

 that samples preserved, whether in a cellar or re- 

 frigerator, for close upon seven months contained a 

 very large number of micro-organisms, so that in these 

 examinations there was no evidence of a gradual falling 

 off of the numbers, but, on the contrary, rather of an in- 

 crease taking place during storage. These results con- 

 tradict those of Leone and Sohnke, who, as pointed out 

 above, found a diminution in the numbers on standing; 

 but, as these investigators only examined a compara- 

 tively small number of samples, it is quite possible that 

 in the individual bottles opened by them there may 

 have been originally only a small number present. 



As regards the experiments made on the powers of 

 multiplication possessed by non-pathogenic bacteria 

 when introduced into seltzer-water, the results varied 

 according to the nature of the particular organism em- 

 ployed. 



Thus the Mierococcus aurantiacus (see p. 501) multi- 

 plied enormously up to the thirteenth day ; on the 

 sixteenth day a diminution was observed, and after 

 eighteen days it was no longer demonstrable. 



The Bacillus prodigiosus (see p. 440), even after a 

 few days, began rapidly to decline in numbers, so much 

 so that in some cases no trace of it could be found 

 after between five and nine days, and the longest 

 period in which its presence was still apparent was ten 

 days. 



Pink yeast (Rosa Hefe) behaved in a similar manner 

 to the Bacillus prodigiosus. 



