STUDIES ON SOIL PROTOZOA. 



By ANDREW CUNNINGHAM, B.Sc. (Edin.), 

 Research Scholar in Bacteriology. 



[From the Laboratorium fiir Bakteriologie am Landwirtschaftlichen 

 Institut der Universitdt, Leipzig.) 



I. Introduction. 



The work discussed in this paper is a continuation of that described 

 in a previous communication to the Centralblalt fiir Bakteriologie'^. 

 Unfortunately it has been found impossible to bring all the problems 

 taken up to a satisfactory conclusion in the time available. And as, 

 owing to unforeseen circumstances it is necessary, for the present at 

 least, to leave this subject, the results so far as they have been arrived 

 at are brought together in this publication and the lines on which it 

 had been intended to work are indicated. It is hoped, however, that 

 an opportunity of continuing this work on the soil Protozoa may 

 present itself at some future date. 



The points which will be dealt with here are : 



The dilution method and its application to the enumeration of protozoa 

 in soils. 



The effect of protozoa on the numbers of bacteria in ammonifying 

 solutions and on ammoniflcation in solution tests. 



The effect of inoculations of protozoa on the bacterial content of 

 partially -sterilised soils. 



II. The Dilution Method. 



The dilution method has already been applied to the enumeration 

 of protozoa in soils by Rahn-. He used as media peptone and sugar 

 solutions incubated for 7-14 days. The dilutions were made in the 

 usual way and at the end of the incubation period the cultures were 



1 CentraWl.f. Bakt. Abt. u. Bd. 39, pp. 596-610. 

 = Ibid. Bd. 36, p. 419. 

 Joiuii. of Agrio. Sci. vn 4 



