78 BACTERIOLOGY. 



As a rule, the colony-formations seen upon gelatin 

 are much more characteristic than those which develop 

 on agar-agar, and for this reason gelatin is to be pre- 

 ferred when circumstances will permit. Both gelatin 

 and agar-agar may be used in the preparation of plates 

 and Esmarch tubes, subsequently to be described. 



