16 THE ROYAL SOCIETY OF CANADA 



Experiment IV. 

 Table IVa. 

 Plot Sown to Grass for Three Years. 

 Average number of bacteria (in millions) per gram of soil at different depths. 



Experiment IV. 



Table IVb. 



Plot Sown to Grass for Three Years. 



Average number of bacteria (in millions) per gram of soil at different depths 

 on different media. 



