BACTERIAL CLASSIFICATION 19 



taken to mark a natural species or variety, and the char- 

 acters which vary together must form the most important 

 basis for the establishment of the larger groups. By such 

 a method alone it is possible to locate those mountain 

 peaks in the chain of bacterial variations which rightly 

 deserve generic and specific names, altho records of 

 the characters of individual races by the decimal system 

 are of the greatest value in mapping out intermediate 

 regions. Only the statistical study of numerous individ- 

 uals by comparable quantitative methods can reveal the 

 general laws of natural classification among the bacteria ; 

 and this study must be made in each group with an open 

 mind free from arbitrary predispositions." 



On the one hand, the results obtained from this inves- 

 tigation emphasized the extreme variability of the cocci. 

 Almost every character measured showed a wide range 

 of variation; and intergrading forms were so abundant 

 as to make it wholly impossible to draw sharp and 

 arbitrary lines of demarcation. When, on the other 

 hand, the series was examined with the idea of discern- 

 ing central types, modes on the curve of frequency, and 

 when the correlation of the various characters was 

 studied, the problem began to solve itself. 



In the first place, two major divisions or subfamilies, 

 within the general group of the Coccaceae, were obvi- 

 ously apparent. The first group, comprising most of 

 the forms from the body, showed, as a rule, chains and 

 irregular cell-grouping, stained by Gram, yielded a 



