438 



Observations on Soil Protozoa 



* In the above table C denotes that the supernatant fluid was devoid of protozoa and 

 that therefore the soUd matter had completely withdrawn them from the suspension, 



number of organisms from a suspension. Thus when -25 gram of either 

 sand, soil or clay was employed there was retained only l/ith of the 

 number of organisms retained by 1 gram of the substance. For these 

 results see Tables V and VI. 



Effect of varying the Time Factor. 



The preceding investigations were all performed with the time 

 factor constant, which had been arbitrarily fixed at 10 minutes. In 

 these final experiments this factor was varied. The results were not 



