SUBFAMILIES AND GENERA OF COCCACE^ 107 



Gelatin frequently liquefied. Nitrates may or may not be 

 reduced. 



The last group — which includes the red chromogenic 

 cocci — is so individual in its characteristics that even our 

 small series of cultures was sufficient to establish it as a 

 clearly defined type. Twenty-five of our 500 cocci formed 

 a reddish or pinkish growth. The shade of color produced 

 varied considerably, and these organisms were scattered 

 rather irregularly over the last three columns of the chart 

 of color distribution (see frontispiece); but the group 

 proved to be an exceptionally homogeneous one. Only 

 one culture out of the 25 came from a parasitic habitat; 

 and only 2 of the 25 showed two successive positive Gram 

 reactions. In fermentative power the red cocci corre- 

 sponded closely with the yellow types. It will be noticed 

 in Figure II that, like the micrococci and sarcinse, they 

 center about a low acidity; and there is even less 

 variation among the red than among the yellow forms. 

 The growth masses of the red cocci were on the whole 

 more luxuriant than those of any other type. Twenty- 

 three of the 25 strains were classed as abundant in 

 growth. 



In these aspects the red cocci correspond with the 

 other types of the Metacoccaceae. They form apparently 

 the extreme end of a series which begins with some of the 

 less vigorous micrococci. Among the red forms the 

 saprophytic habit, the negative Gram stain, and the vigor 

 of surface growth all reach a maximum. In chromogenic 



