172 



JAMES M. SHERMAN 



and Hutchinson reveals the fact that in some of the tests the 

 treated soils which were reinoculated with 5 per cent of untreated 

 soil did not show an appreciable depression in the number of 

 bacteria, and they qualify their conclusion on this point with the 

 statement that, "the harmful factor is not invariably transmitted 

 to the same extent from the untreated to the partially sterihzed 

 soil and in a few cases indeed it is not transmitted at all." 



In the experiments which were carried out in this laboratory 

 the partially sterilized soils were reinoculated with 1 per cent 

 of untreated soil; since at least 1 kgm. of soil was used in each 

 pot the inoculum never consisted of less than 10 grams of normal 

 soil. It could hardly be doubted that this amount of soil would 

 be sufficient to transplant the group of organisms, if such exist, 

 which act as a limiting factor upon the bacterial flora. 



The work wliich has been done on the reinoculation of par- 

 tially sterilized soils (Tables XXXII to XXXIV) fails to give 

 any indication that a harmful factor is thus introduced. It 

 would appear, on the other hand, that if reinfection of the treated 



TABLE XXXII 



Effect of reinoculation of treated soil with untreated soil {treatment of 2 -per cent 



toluene) 



TABLE XXXIII 



Effect of reinoculation of treated soil with untreated soil (treatment 1 'per cent toluene: 



evaporated) 



