SUBFAMILIES AND GENERA OF COCCACE^ 109 



the same color, the same general cultural and biochemical 

 properties, the same peculiar relation to gelatin and 

 nitrates. There is no established distinction to be deferred 

 to here as in the case of Micrococcus and Sarcina; and 

 there is clearly no ground for creating a new distinction 

 between forms so closely allied as all the red cocci appear 

 to be. We have, therefore, defined the genus Rhodococcus 

 so as to include all forms which exhibit the peculiar 

 complex of characters which has been described above, 

 whether their cells occur in packets or in smaller and less 

 regular groups. 



Genus VIII. Rhodococcus (Winslow and Rogers). 

 Saprophytes. Cells in groups or regular packets. Gen- 

 erally decolorize by Gram. Growth on agar abundant, 

 with formation of red pigment. Dextrose broth slightly 

 acid, lactose broth neutral. Gelatin rarely liquefied. 

 Nitrates generally reduced to nitrites, but not to ammonia. 



