SUBFAMILIES AND GENERA OF COCCACE^E 8 1 



all the Medium Cadmium Yellow, and the lighter chromas 

 of Orange Yellow we have called Yellow (Light Cadmium 

 Yellow, IV-IX, — Medium Cadmium Yellow, — Orange 

 Yellow, I-IV). The deeper chromas of Orange Yellow 

 and all the Cadmium Orange column have been called 

 Orange (Orange Yellow, V-IX, — Cadmium Orange). 

 The last three columns \have been grouped as Red. It 

 will be noticed that these divisions correspond, as nearly 

 as possible, to the natural divisions between the centers 

 of variation indicated on the plot. Grouping the cultures 

 in this manner the relation between habitat and chromo- 

 genesis may be brought out as indicated in the table below. 

 These figures show that the orange cocci are charac- 

 teristically parasitic forms, while the yellow and red pig- 

 ment producers occur primarily in other environments. 

 The case is not so clear in regard to the cocci we have 

 classified as White. We had only 40 cultures in this 

 class and 13 of them were isolated from the air, which 

 unduly increases the saprophytic group. Other consider- 

 ations will show that the white cocci, like the orange 

 ones, are primarily parasitic. 



HABITAT OF COCCI OF VARIOUS CHROMOGENIC CHARACTER- 

 ISTICS. 



* Including air forms. 



