STUDIES ON SOIL PROTOZOA 



43 



That the high protozoan content noted above is not pecuhar 

 to Wisconsin soils is showTi by the data obtained from three 

 Virgiaia soils and one Tennessee soil given in Table II. These 

 samples were from representative soils in a good state of culti- 

 vation. 



The figures of the foregoing tables show that, in the sixteen 

 soils recorded, in every soil protozoa were found in both samples 

 of the 1/1,000 of a gram dilution, while of the total of 32 dilu- 

 tions representing 1/10,000 of a gram each, 18 revealed the pres- 

 ence of protozoa. When we consider that, (1) it is extremely 

 improbable that every individual protozoan grows when taken 



TABLE II 

 The approximate number of protozoa in Virginia and Tennessee soils 



A and B represent the duplicate samples of each soil. 

 + = presence of protozoa. 



— = no protozoa present. 



* Balantiophorus elongalus found in addition to flagellates. 



from the soil and introduced into a hquid medium; (2) the 

 liquid medium used is probably not adapted for the growth of 

 all protozoan inhabitants of the soil ; and (3) some of the samples 

 representing only 1/10,000 of a gram contained three distinct 

 types of animal organisms, the statement that the average fer- 

 tile soil contains about 10,000 protozoa per gram seems con- 

 servative.- 



In cultures inoculated with 1/1,000 of a gram of soil, a variety 

 of flagellates are usually to be observed. As seen from the above 



- it should be borne in mind that these data are not intended to give an accu- 

 rate estimate of the numbers of protozoa in soil, but only to show whether they 

 occur in numbers sufficient to be regarded as a possible factor in soil fertility. 



