178 RELATIONSHIPS OF THE COCCACE^E 



has led us, however, to the belief that, in spite of its insta- 

 bility, the power of pigment production is, under natural 

 conditions, correlated with the most important group 

 differences among the cocci. The facts which pointed 

 to this conclusion have been fully summarized in Chap- 

 ter IV, and it is unnecessary to repeat them here. It 

 appeared that the orange and white forms were charac- 

 teristic of the normal or diseased body, while the lemon- 

 yellow cocci usually occurred as saprophytes in earth, 

 water, or air. The former generally stained by Gram 

 and produced acid in dextrose and lactose. The latter 

 were, as generally, Gram-negative and, as generally, 

 failed to ferment sugars. The orange and white forms 

 clearly belong to the great division of the Coccaceae, 

 adapted to life on or in the animal body; the yellow forms 

 belong to the other great division which includes the 

 saprophytic cocci. Furthermore, the orange and white 

 types differed from each other in their action upon gela- 

 tin as well as in chromogenesis. Among the liquefying 

 organisms in the two groups the orange chromogens were 

 twice as active as the white forms. 



Since several well-marked subtypes could be recog- 

 nized within each of these two main types, it seemed most 

 convenient, as stated in Chapter IV, to recognize the 

 orange forms (actively liquefying, if at all) and the white 

 forms (with only moderate liquefying power) as distinct 

 generic groups under the names Aurococcus and Albo- 

 coccus. It is understood of course, as in other cases, that 



