CLASSIFICATION OF ANAEROBIC BACTERIA 541 



SPECIFIC AND GENERIC CHARACTERS 



No one will dispute that the decision as to the line between 

 specific characters and generic characters lies with the system- 

 atist who, though he have a previous knowledge of many other 

 groups, has confined his attention to one group, and not with 

 the systematist who organizes the published work of others. 

 In different groups these boundaries vary somewhat. But in 

 general the following definition will probably be accepted for 

 such types of material as we are unable to examine thoroughly 

 by a biometric method. Strains of bacteria that regularly and 

 consistently differ from each other in certain characters that we have 

 come to recognize as significant may be assigned to different species. 

 These characters may be quantitative in their nature. It lies in 

 the hands of each worker to decide what the value of these characters 

 is. An arrangement made without reference to biometric data 

 is in any case bound to be tentative. Generic characters are 

 based on qualitative properties. As a working system the follow- 

 ing classification of specific and generic characters for organisms 

 of the anaerobic group is suggested: 



Generic characters, qualitative: 



Qualitative chemical action: behavior on usual laboratory 

 media (excepting the fermentation of milk). 



Staining reaction and general morphology of individuals. 



General habits of colony formation. 



Pathogenic action. 

 Specific characters, quantitative: 



Quantitative chemical action: behavior on carefully standard- 

 ized media; hydrogen-ion end point attained as a result 

 of specific enzyme action. 



Sugar fermentations if not subject to active mutation. 



Peculiar habits of the morphology of individuals. 



Exact behavior of colony formation on a standard medium. 



Details as to pathogenic action. 



In studying my material, I find abundant justification for the 

 appUcation of properties of this sort. With such characters to 

 build upon, a more detailed structure, more exactly expressing 



