CLASSIFICATION OF BACTERIA. IQI 



The grouping together of the different species 

 according to the character of the colonies in 

 nutrient gelatine (Figs. 69, 70) is also of question- 

 able advisability. These characters can hardly 





FIG. 70. COLONIES ON NUTRIENT AGAR-AGAR, X 60. 



be considered to be of sufficient importance, or 

 indeed in many cases to be sufficiently constant, to 

 serve by themselves for this purpose. In many 

 cases a slight variation in the composition of the 



FIG. 71. COLONY OF BACILLUS ANTHRACIS, x 60. From a cover-glass 

 impression-preparation, stained with gentian- violet. 



nutrient medium may considerably affect the ap- 

 pearances of the colonies. At the same time, 

 the appearances are very characteristic of cer- 

 tain species of bacteria (Fig. 71), and in other 



