BACTERIA IN THE SOIL I43 



I. The Denitrifying Bacteria, A group whose function 

 has been elucidated in recent years (largely by the investiga- 

 tioiis of Professor Warington) are held responsible for the 

 breaking down of nitrates. With these may be associated 



A Method of Growing Cultivations in a Vacuum 



OVER PYROGALLIC SOLUTION 



the Decomposition or Putrefactive Bacteria, which break 

 down complex organic products other than nitrates into 

 simpler bodies. 



2, The Organisms of Nitrification, To this group belong 



