280 BIOCHEMICAL PEOCESSES OF THE SOIL 



survey as permanent a value as possible the investigations were 

 not confined to the narrow issue whether soil protozoa do or 

 do not interfere with soil bacteria, but they were put on the 

 broader and safer lines of ascertaining whether a trophic 

 protozoan fauna normally occurs in soil, and, if so, how the 

 protozoa live, and what is their relation to other soil 

 inhabitants. 



The first experiments were made by Goodey * mainly with 

 ciliates, and indicated that these organisms were present only 

 as cysts. Subsequent investigations, however, by Martin and 

 Lewin established the following conclusions : t 



1. A protozoan fauna in a trophic state normally occurs in 

 soils. 



2. The trophic fauna found in the soil differs from that 

 developing when soil is inoculated into hay infusions : the 

 forms which appear to predominate in the soil do not predomi- 

 nate in the hay infusions, and vice versa, the forms predominating 

 in the hay infusions do not necessarily figure largely in 

 the soil. 



3. The trophic fauna is most readily demonstrated, and is 

 therefore presumably most numerous, in moist soils well 

 supplied with organic manures ; e.g., in dunged soils, greenhouse 

 soils, sewage soils, and especially glass-house "sick" soils. 



Finally, the latest experiments by Goodey J have shown that 

 when this trophic fauna is introduced into partially sterilised 

 soils the bacterial numbers are brought down. The earliest 

 attempts to carry out this experiment failed, as already stated, 

 only one successful experiment by Cunningham being on 

 record. It was not till Goodey discovered the conditions for 

 successful inoculation that it could be carried out. Goodey 

 found that mass cultures of protozoa failed when introduced 



* Goodey, Roy. Soc. Proc., B. 86 (1913), 427-451. 



t Martin and Lewin, Phil. Trans., 205 (1914), 77-94; and J. Agric. Set., 

 7 (1915), 106-119. 



J Goodey, Roy. Soc. Proc., B. 89 (1916), 297-314. 



Centr. Bakt. Par., August 1914, and J. Agric. Sci., 7 (1915), 49-74. 



