244 RELATIONSHIPS OF THE COCCACEiE 



so only slowly and feebly. There is no evidence for a dis- 

 tinct type center of actively liquefying forms, separated on 

 the Curve of Frequency from another center of non-lique- 

 fiers, such as occurs in Aurococcus, Albococcus, Micro- 

 coccus, and Sarcina. It seems best, therefore, not to make a 

 separate species for the slow liquefiers. The most prob- 

 able conclusion, in the light of present knowledge, is that 

 the red chromogens, in relation to gelatin, form a single 

 group, characterized by entire failure to liquefy or by very 

 slow and feeble action. 



There remains only the property of nitrate reduction as 

 a means for differentiating species among the rhodococci. 

 Here our series, altho small, seems to indicate the existence 

 of two distinct types, one forming nitrites in nitrate solution, 

 the other failing to do so. The commonest type accord- 

 ing to our somewhat limited observations is a form which 

 reduces nitrates in the manner peculiar to the genus. Of 

 our twenty-five strains fifteen fall under this head. In 

 other respects they correspond to the general type of the 

 genus as previously described. Five are packet-formers, 

 and three, slow liquefiers. 



The only published description of a strongly reducing, 

 red coccus which has come to our attention is that of 

 the organism which Dyar identified with Diplococcus 

 roseus of Bumm. Dyar calls it Merismopedia rosea 

 (Bumm). This form was really first named by Flugge 

 (1886) as M. roseus, a year after Bumm described it as 

 the "rose colored diplococcus"; but it was Dyar in 1895 



