20 RELATIONSHIPS OF THE COCCACE^ 



meager or only fair surface growth, formed acid in 

 carbohydrates, and produced no pigment, or a white 

 or orange one. The other group, from earth and water 

 for the most part, often showed packets, decolorized by 

 Gram, grew well on artificial media, failed to ferment 

 carbohydrates, and produced a yellow or red pigment. 

 Each character was occasionally found in the group 

 where it did not usually occur; but the correlation of 

 properties in the vast majority of cases was very 

 strong. It was a striking fact that the two chief 

 divisions among the Coccaceae corresponded to the 

 two markedly different environments which exist in 

 nature, the body of higher organisms and the outer 

 world. A close correspondence with environmental con- 

 ditions should naturally be expected among such sim- 

 ple asexual organisms as the bacteria; and it increased 

 our confidence in the reality of the groups established 

 to find each of them localized so sharply in one or other 

 of the two main environments. 



Within the subfamilies we found a second grade 

 of group -individuality, forming what may be called 

 genera, marked by the association of a smaller number 

 of characters than the subfamilies, but still defined by 

 the correlation of several independent properties. Here, 

 to our surprise, the property of chromogenesis appeared 

 of supreme importance. 



Six groups of species, which seemed to us of generic 

 rank, appeared among the cocci studied. Each was 



