GENERAL SYSTEMATIC BACTERIOLOGY 99 



I. Gram -positive. Slender, sometimes 

 clubbed rods. 



Corijnebacterium 

 II. Gram-negative. Rods sometimes 

 form threads. Characteristic 

 honey like growth on potato. 

 Pfeifferella 

 FF. Not animal parasites. Cells staining unevenly 

 and with branched or filamentous forms at cer- 

 tain stages. Never acid fast. 

 G. Metabolism simple, growth processes in- 

 volving oxidation of alcohol or fixation of 

 atmospheric nitrogen (latter in symbiosis 

 with green plants). 



H. Cells minute, sjrmbiotes in roots of 

 leguminous plants. 

 Rhizobium 

 HH. Oxidizing alcohol, branching forms com- 

 mon Acetobacter 



GG. Not as above. Proteus-like colonies. 



H. Not attacking carbohydrates. Gram + 

 Zopfius 

 HH. Fermenting glucose and sucrose. Gram — 

 Proteus 

 EE. Regularly formed rods. 



F. Metabolism simple, growth processes involving 

 oxidation of carbon, hydrogen or their simple 

 compounds or the fixation of atmospheric nitro- 

 gen. Nitrobacteriaceae. 



G. Fixing nitrogen or oxidizing its compounds. 

 H. Fixing nitrogen. 

 Cells large; in soil. 



Azotobacter 

 HH. Oxidizing nitrogen compounds. 

 I. Oxidizing ammonia. 

 Nitrosomonas 

 II. Oxidizing nitrites 

 Nitrobacter 

 GG. Not as above. 



H. Oxidizing hydrogen. 



Hydrogenomonas 

 HH. Not as above, using simpler carbon com- 

 pounds. 

 I. Oxidizing CO. 



Carboxydomonas 

 II. Oxidizing CH4. 



Methanomonas 



