442 BACTERIOLOGY. 



For general use this method is to be preferred to the 

 others that have been mentioned. 



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 

 in sterilized water and then making plates immediately 

 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 such organisms practised 

 in connection with the ordinary methods. 



