38 METHODS OF STUDYING MICROORGANISMS 



from which this single organism comes the bacteri- 

 ologist colors it by certain aniline or vegetable dyes, 

 of which there are a large number. It is practically 

 impossible certainly to identify any bacterium by a 



FIG. 10 



Showing certain macroscopic characteristics of colonies. Natural size. 

 (Abbott.) 



simple examination of a stained preparation under 

 the microscope. The observer, however, does form a 

 tentative opinion as to its probable nature, and pro- 

 ceeds to introduce some of the material into a nutrient 

 medium which he considers best adapted to its develop- 



