19: 



C.-E. A. WiNSLOw AND Anne F. Rogers 



gens were chiefly parasites, the yellow and red chromogens chiefly 

 saprophytic forms. The same distinction is shown in Table ^t, with 

 regard to cell-grouping. The white and orange cocci only rarely, 



the latter very rarely, show packets. The yellow and red forms, 

 on the other hand, show the sarcinae-grouping almost half the time. 



TABLE 34. 

 Correlation between Chromogenesis and Gram Stain. 



The reaction to the Gram stain exhibits a still more perfect 

 correlation. Among the whites and oranges (the parasitic forms) 

 positive Gram reactions predominate, and negative ones are rare. 

 Among the saprophytic yellows and reds conditions are symmetri- 

 cally reversed. 



TABLE 35. 

 Correlation between Chromogenesis and Surface Growth. 



Surface Growth 



Very faint 



Meager 



Good 



Abundant 



Very heavy 



Red 



o 

 o 



I 



24 



o 



A comparison of the general vigor of growth shows that each 

 color has its own relation. Among the white forms, two maxima 

 appear, one under "very faint" growth and one under "abundant" 

 growth. This is because this group is a compound one, including 

 forms which give a really w^hite growth abundant in amount, and 

 the feebly growing streptococci which are classed here, although 

 they produce no pigment at all. The yellow and orange chromo- 



