H. B. Hutchinson and A. C. Thaysen 



47 



Soil Extract 

 Salt, Solution 



■g 1.000 



500 



24 

 Time in hours 



Curve I. Growth of Bac. iirndifiiosiis in extracts of untreated soils 

 (Rothamsted and Jlillhrook) and in salt solution. 



1.000 



500 



■ Untreated Extract 



Heated Extract 



4 8 



48 



72 



24 



Time in hours 



CuKVE II. Growth of Bac. prodigiosus in untreated and heated soil extracts 



(mean of 6 soils). 



