STUDIES ON SOIL PROTOZOA 



65 



TABLE XXIV 

 Effect of Flagellate B upon the number of bacteria in soil 



Mixture of Protozoa 



It was thought that, although none of the individual protozoa 

 which were tried in pure culture were able to decrease the number 

 of bacteria in soil to a measurable extent, this might be accom- 

 plished through the combined action of all of them. Two experi- 

 ments were performed in which a comparison was made of pro- 

 tozoa-free soil and of soil containing the six types of protozoa 

 used in the preceding tests. For these tests the soils were 

 allowed to incubate for two months as it might be contended 

 that one month was not sufficient time to allow the "detrimental 

 factor" to develop. These trials, in keeping with all of the tests 

 which have been made with the individual organisms, gave 

 wholly negative results. 



TABLE XXV 

 Effect of mixture of protozoa upon the number of bacteria in soil 



Test 1 



