BACTERIOLOGICAL STUDY OF THE SOIL. 611 



It must be borne in mind that many of the ground 

 organisms belong to the anaerobic group, so that iia 

 these studies this point should be remembered and the 

 methods for the cultivation of such organisms practised 

 in connection M'ith the ordinary methods. It must also 

 be remembered that the nitrifying organisms, every- 

 where present in the ground, cannot be isolated by the 

 ordinary methods, and will not appear in plates made 

 after either of the above plans. The special devices 

 that have been arranged for their cultivation will be 

 found in the chapter on soil organisms. 



