198 



MICRO-ORGANISMS IN WATER 



Purification of Water by means of Agitation with solid Particles 



(Kriiger) 



Pulverised and Sterilised Potter's Clay 

 Temperature at which vessels were kept = 7 C. 



1 Water was only slightly turbid after 12 hours. 



Pulverised and Sterilised Calcium Carbonate 

 Temperature at which vessels were kept varied between 8-10 C. 



1 Very slightly turbid in the lower layers after 1!) hours. 



2 Ditto after 26 hour?. 



Finely Sifted and Sterilised Infusorial Earth 

 Temperature at which vessels were kept varied between 6-9 C. 



1 Still slightly turbid after standing 20 hours. 

 - Ditto after standing :;u hours. 



