54 JAMES M. SHERMAN 



TABLE IX 

 Number of bacteria in soils kept at different temperatures 



In the soils kept at 37°C. there was the same difference between 

 the numbers of bacteria in the soils containing and free of pro- 

 tozoa as in the soils incubated at room temperature. The great- 

 est difference was found in the soils incubated at 10°C., which 

 fact is opposed to the protozoan theory, unless it be assumed 

 that the protozoa act better at low temperatures. Such an 

 assumption is not in accord with the known facts concerning 

 them. 



Effect of moisture content upon bacteria in soils with and without 



protozoa 



It is generally acknowledged that protozoa require a larger 

 amount of moisture than bacteria. An experiment was made 

 with soils of a very low moisture content in order to eliminate 

 the action of the ''detrimental factor," if such exists in the soil. 

 Soil with an optimum moisture content of 18 per cent was dried 

 so as to contain only 8 per cent water. This soil was steriliz'ed 



TABLE X 



Number of bacteria in soils of low moisture content 



