472 SOILS: PROPERTIES AND MANAGEMENT 



Some typical results of investigations by Russell and 

 Hutchinson on the effect of partial sterilization on bac- 

 teria numbers, ammonia production, and presence of 

 protozoa are given below : — 



390. Greig-Smith's theory. — An entirely different 

 explanation of the effect of partial sterilization on soils 

 has been advanced by Greig-Smith. 1 He states that 

 when disinfectants are applied to the soil their action is 

 a double one. They kill the less resistant bacteria, and 

 dissolve from the surfaces of the soil particles a waxy 

 covering, to which he has given the name " agricere." 

 The surviving bacteria, among which are the beneficial 

 ones, are able to develop more rapidly because of the 

 greater accessibility of the food supply which the re- 

 moval of the " agricere " has exposed. 



Greig-Smith holds that heat destroys substances toxic 



1 Greig-Smith, R. The Bacteriotoxins and the "Agricere" 

 of Soils. Centrlb. f. Bakt., II, Band 30, Seite 154-156. 1911. 



