174 



JAMES M. SHERMAN 



TABLE XXXV 



The number of bacteria in treated and untreated soils at different temperatures 



These data are not sufficient to base any conclusions upon 

 but it can not be said they indicate very much, either in favor 

 of the protozoan theory or against it. It will be seen that the 

 greatest difference in the numbers of bacteria in the treated 

 and untreated soils was at 10°C., a point not in favor of the pro- 

 tozoan theory. On the other hand, the least difference was found 

 at 37 °C., which point may support the theory of Russell and 

 Hutchinson. 



It was decided to carry out another experiment at 37°C. in 

 order to throw more light on this point. Instead of using soils 

 which had been previously treated, the soils were first placed 

 at 37°C. and allowed to incubate at that temperature for one 

 month. Half of them were then treated with 2 per cent carbon 

 bisulphide. If the protozoan theory is correct the antiseptic 

 should have very httle effect at this high temperature. One 

 month after treatment bacterial counts were made. The results 

 obtained are given in Table XXXVI. 



The results are very striking; a difference of over ten fold in 

 the number of bacteria in the treated and untreated soils being 

 found. This observation indicates strongly that the beneficial 

 .action of volatile antiseptics in soil is not to be explained by 



