178 MICRO-ORGANISMS IX WATER 



and containing about 30,000 organisms in 1 c.c.). The 

 filter was first sterilised and then fed with this infected 

 water, an unfiltered drop of which was examined at the 

 commencement of the experiment, and filtered drops at 

 the end of twenty-four hours. The cholera bacilli were 

 found in the unfiltered water on the first and second 

 day, but at the end of forty-eight hours, when it 

 had become very putrid, none were detected. They 

 were present at the end of twenty-four hours in the 

 filtered water, and were still found at the end of thirty- 

 five hours, but none were discoverable at the end of 

 forty-eight hours. The typhoid bacilli were found in 

 the unfiltered water in large numbers at the end of 

 seventy-three hours, when the investigation was discon- 

 tinued ; in the filtrate they did not appear until after 

 forty-eight hours, and were still present in large num- 

 bers at the end of seventy-three hours. It should be 

 pointed out that in consequence of the large admixture 

 of broth to the water under examination the latter must 

 have been very highly charged with nutritive material 

 favouring the growth and multiplication of the bacteria 

 present, and therefore the conditions are different from 

 those under which natural waters actually containing 

 typhoid and cholera germs might be subjected to filtra- 

 tion. Also as regards the presence of typhoid bacilli 

 in the filtrate, it is to be regretted that Kirchner gives 

 no particulars as to the manner in whirl i these were 

 identified, a very serious omission, considering the 

 ease with which a wrong diagnosis of their presence 

 may be made. (For the important services rendered 

 by the Chamberland and Berkefeld filters in the labora- 

 tory, see p. 4.) 



Schofer l in examining the Berkefeld filter with the 



1 ' Ueber das Verhalten von pathogenen Keimen in Kleinfiltern.' 

 Centralblatt fiir BaUcriologie, vol. xiv. p. 685, LSI);). 



