198 



MICRO-ORGANISMS IN WATER 



Purification of Water by means of Agitation with solid Particles 



(Kriiger) 



Pulverised and Sterilised Potter's Cla/y 



Temperature at which vessels were kept = 7° C. 



* Water was only slightly turbid after 12 hours. 



Pulverised and Sterilised Calcium Carbonate 

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



' Very slightly turbid in the lower layers after 19 hours. 

 = Ditto after 26 hours. 



Finely Sifted and Sterilised Infusorial Earth 

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



Still slightly turbid after standing 20 hours, 

 ■ Ditto after standing 30 hours. 



