BY It. GRKIG-SMITH. 



671 



at the same temperature. I believe the moisture and temperature 

 are of more importance in modifying the bacterial content of soils 

 than one would imagine, and experiments concerning these influ- 

 ences are in progress. In heated soils, the bacteria grow very 

 rapidly at first, then, as the toxin accumulates, the numbers fall 

 almost as sharply, after which they slowly rise. With chloroform 

 alone, the numbers increase slowly and steadily, as if nutrients 

 were being slowly utilised. 



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51 



JO doLj^i 



The extracts with which the soils had been treated, in these ex- 

 periments, contained not only protozoa and bacteria, but also 

 nutrients and toxins, as I have already shown in the first paper of 

 this series. As it is just possible tliat these two latter substances 

 miglit have a certain, though small, influence in increasing or 



63 



