SUBGROUPS AND GENERA OF THE BACTERIACEAE 45 



The type species is Hemophilus influenzae, ( ) comb. nov. 



the cause of influenza. 



Subtribe III. Rhizobiinae Subtrib. nov. 



Rod-shaped organisms, securing their growth energy by the 

 oxidation of carbonaceous compounds, as carbohydrates, alcohol, 

 etc. Do not require serum, etc. Not parasitic in animals. 



The following key gives the principal differential characters 

 of the genera : 



Key to the genera of Rhizobiinae 



A. Not fixing atmospheric nitrogen; securing growth energy usually by the 



oxidation of ethyl alcohol to acetic acid Genus 1. Mycoderma 



B. Capable of fixing appreciable amounts of atmospheric nitrogen. Grow well 



on nitrogen-free media, 

 a. Small motile rods, with abundant involution forms, frequently living 

 in root nodules of the higher plants (legumes). . .Genus 2. Rhizobium 

 h. Not symbiotic. Cells larger, plump, almost spherical in some cases. 



Genus 3. Azotobacter 



Genus I. Mycoderma Persoon, 1822, p. 96 emended 



Synonyms : 



Ulvina Kuetzing, 1837, p. 26 

 Umbina Naegeli, 1849 

 Bacteriopsis? Trevisan, 1885, p. 103 

 Acetobacter Fuhrmann, 1905, p. 8 

 Acetimonas Jensen, 1909a, p. 312 



Cells rod-shaped, frequently in chains, non-motile usually, 

 without spores. Obligate aerobes, growing usually as a film on 

 the surface of alcoholic solutions, transforming the alcohol to acetic 

 acid. Involution forms often developed and quite characteristic. 



The type species is Mycoderma aceti Thompson? 



There is some doubt as to the appropriateness of Mycoderma 

 as the name of this genus. It is possible that it should be re- 

 served for the yeasts. 



