g6 RELATIONSHIPS OF THE COCCACE^ 



erally Gram-negative, form good to abundant surface 

 growth, produce only a slight acidity in dextrose and usu- 

 ally none in lactose. Minor characteristics are peculiar 

 to each of the color-types. 



On the whole the evidence seems amply sufficient to 

 show that these four types constitute natural groups 

 among the Coccaceae. Each of them includes several 

 distinct subtypes, characterized by such peculiarities as 

 are ordinarily considered of specific value among bac- 

 teria. Each is marked by the correlation of other 

 properties, of still greater systematic importance, which 

 characterize the type as a whole. It seemed to us, there- 

 fore, that the four main types might well be given generic 

 rank. It is a matter of more or less arbitrary opinion 

 whether a given group of bacteria shall be considered 

 a genus or not; but convenience certainly demands an 

 increased use of generic names among these organisms. 

 We have, therefore, separated the white and orange groups 

 of the Coccaceae from the genus Micrococcus with which 

 they are generally included, under the new generic names 

 Albococcus and Aurococcus; and have separated the red 

 forms from the genera Micrococcus and Sarcina under the 

 new generic name Rhodococcus (Winslow and Rogers, 1906). 



The characteristics of the genera into which the Cocca- 

 ceae are thus divided will be made clearer by the tabular 

 statement on page 97 and by the diagrammatic represen- 

 tation of their respective average characters in Figure I. 



