THE METHODS OF CULTIVATING MICROBES 61 



a microbian mixture) separate themselves from each 

 other ; and from these colonies pure cultivations of 

 each microbe may be obtained by carefully re- 

 inoculating a number of tubes containing sterilised 

 nutrient gelatine or agar-agar. Plates of gelatine or 

 agar-agar (Fig. 24) may also be reinoculated in a 



FIG. 24. A PLATE-CULTIVATION OF SPIRILLUM TYBOOENUM. 



A, Colonies growing on nutrient gelatine (sterilised). 



B, The spirillum x 1265. 



similar manner. First, second, and third attenua- 

 tions may be obtained by this mode of cultivation. 

 Both the macroscopical and microscopical appear- 

 ances should be noted. To examine the growth 

 under low power one of the plates should be placed 

 upon the stage of the microscope, and the appear- 



