42 



JAMES M. SHERMAN 



satisfactory results as has soil extract, in the comparison made 

 at this laboratory. 



Soil extract prepared by boiling one part of soil in three parts 

 of distilled water, filtering clear, and adding a small excess of 

 CaCOs, has been used. This has been modified by using only 

 one part of soil in nine parts of water and one part of a one 

 per cent hay extract, plus CaCOs. The presence of this small 

 amount of hay extract does not appear to exert any inhibitory 

 effect upon the flagellates, while the ciliates seem to be benefited. 

 In sampling soil not less than ten grams have been taken, and 

 duplicate dilutions have always been made. The cultures have 

 been incubated at 20°-25°C. and examined every few days for a 

 period of about ten days. 



Results 



The data obtained on twelve Wisconsin soils, representing 

 various types under different treatments, are tabulated in Table 

 I. 



TABLE I 

 Approximate number of protozoa in various Wisconsin soils 



A and B represent the duplicate samples of each soil. 



+ = presence of protozoa. 



— = no protozoa present. 



* Colpoda found in addition to flagellates. 



t Amoebae found in addition to flagellates. 



