248 MICRO-ORGANISMS IN WATER 



organisms were discoverable ; again, another water having 

 as many as 25,558 bacteria in a c.c. to start with, after 

 one hour's centrifugal agitation was found to contain 

 only 3,692. Urine was also tried, and the original num- 

 ber of 9,118 micro-organisms per c.c. was reduced, after 

 one hour's centrifugal agitation, to 104. 



Cramer, 1 on the other hand, obtained entirely nega- 

 tive results in similar experiments, for after shaking up 

 a sample of water for 15 minutes, and comparing the 

 plate-cultures with those obtained from the same water 

 which had remained at rest, the mean of 8 experiments 

 yielded 87 microbes per c.c. for the agitated, and 80 per 

 c.c. for the unagitated water. Similar negative results 

 were also obtained by Leone, 1 Miquel, 1 as well as by 

 Tiemann and Gartner. 1 In a paper on the effect of cen- 

 trifugal agitation on the bacteria in milk, Scheurlen 2 

 describes some experiments which he made on their pre- 

 sence in water when submitted to this treatment. An- 

 thrax-spore cultures were employed in sterile distilled 

 water, and it was found that one hour's centrifugal agita- 

 tion produced no effect either upon the numbers origin- 

 ally present, or on the toxic properties of the organisms, 

 for mice on being inoculated with some of the agitated 

 water died exhibiting typical anthrax symptoms. 

 Scheurlen took the precaution of carefully shaking 

 the agitated samples before examining the water, so 

 that any bacteria which might have been precipitated 

 during the centrifugal movement would again be dis- 

 tributed throughout the liquid. The different results 

 previously obtained by Poehl, to which we have referred 

 above, Scheurlen explains as probably due to a neglect 



1 Untersuchung des Wassers, Tiemann-Gartner, 1889, p. 536. 



2 ' Ueber die Wirkung des Centrifugirens auf Bakteriensuspensionen, 

 besonders auf die Vertheilung der Bakterien in der Milch,' Arbeiten a. d. 

 kaiserlichen Gesundheitsamte, vol. vii., 1891, p. 269. 



