BACTERIOLOGICAL STUDY OF SOIL. 191 



BACTERIOLOGICAL STUDY OF THE SOIL. Bacterio- 

 logical study of the soil may be made by either break- 

 ing up small particles of earth in liquefied media and 

 making plates directly from this, or by what is per- 

 haps a better method, as it gets rid of insoluble parti- 

 cles which may give rise to errors : breaking up the soil 

 for investigation in sterilized water and then making 

 plates from the water. 



It "must be borne in mind that many of the ground 

 organisms belong to the anaerobic group, so that in these 

 studies this point should be remembered and the methods 

 for the cultivation of these organisms practised in con- 

 nection with the ordinary methods. 



