IX. SCHIZOMYCETES. 



Classification and Morphology. Bacteria are often 

 classified, in general terms, according to their life 

 functions, into 



, Saprogenic, or putrefactive bacteria ; 

 Zymogenic, or fermentative bacteria ; 

 Pathogenic, or disease-producing bacteria; 



or according to their food requirements into 



Prototrophic, requiring no organic food (e. g., 



nitrifying bacteria) ; 

 Metatrophic, requiring organic food (e. g., 



saprophytes and facultative parasites) ; 

 Paratrophic, requiring living food (obligate 



parasites) ; 



or according to their metabolic products into 



Chromogenic, or pigment-producing bacteria; 

 Photogenic, or light-producing bacteria ; 

 Aerogenic, or gas-producing bacteria; 



and so on. 



Such broad groupings as these have, however, but 

 little practical value when applied to the systematic 

 study of the fission fungi. 



On the other hand, no really scientific classification 

 of the schizomycetes has yet been drawn up, and the 

 varying morphological appearances of the members 

 of the family are still utilised as a basis for classification, 

 as under 



1. Cocci. (Fig. 83). Rounded or oval cells, sub- 

 divided according to the arrangement of the individuals 

 after fission, into 



