400 GENERAL SYSTEMATIC BACTERIOLOGY 



Winslow et al. (Committee Soc. Am. Bact., 1917, p. 551) used the 

 following description, including this family as the first in the Eubacte- 

 riales. 



Organisms usually rod-shaped (sometimes spherical in Nitrosomonas and pos- 

 sibly in Azotobacter). Cells motile or non-motile; when motile with polar, never 

 peritrichous, flagella. Endospores never formed. Obligate aerobes, capable of 

 securing growth energy by the direct oxidation of carbon, hydrogen or nitrogen or 

 of simple compounds of these. Non-parasitic (usually water or earth forms). 



The Committee (1920, p. 200) divided the family into two tribes, 

 Nitrohactereae and Azotobadereae and revised the diagnosis as follows: 



Organisms usually rod-shaped (sometimes nearly spherical in Nitrosomonas, 

 and possibly in Azotobacter). Cells motile or non-motile. Branched involution 

 forms in Rhizobium and Acetobacter. Endospores never formed. Obligate 

 aerobes, capable of securing growth energy by the direct oxidation of carbon, 

 hydrogen or nitrogen or of simple compounds of these. Non-parasitic (except in 

 genus Rhizobium) — usually water or earth forms. 



Bergey et al. (1923, p. 30) has included this family as the first in the 

 order Eubacteriales. 



Nitrobacterieae. A name used by Castellani and Chalmers (1919, 

 p. 932) to designate the first tribe of the family Bacillaceae with the 

 description: "Growth in ordinary laboratory media entirely or al- 

 most entirely absent." Nitrohacterium q.v. is designated as the type 

 genus. 



Winslow et al. (Committee Soc. Am. Bact., 1920, p. 201) used this 

 designation (with the speUing Nitrohactereae) for the first tribe of the 

 family Nitrohacteriaceae, with the description: "Organisms deriving 

 their life energy from oxidation of simple compounds of carbon and 

 nitrogen (or of alcohol)." 



Bergey et al. (1923, p. 31) have followed the committee. 



Nitrohacterium. A generic name proposed by Castellani and 

 Chalmers (1919, p. 933) for the species Nitrohacterium nitrohacter 

 (Winogradsky) Castellani and Chahners. No description is given. 

 It is the single genus of the tribe Nitrobacterieae q.v. 



Nitromicrobium. A name proposed by Stutzer and Hartleb (1899, 

 p. 197) for Nitromicrobium germinans, an organism changing nitrites 

 into nitrates. Cells 0.76-1 x 1-2.5/^, eUipsoidal one end thicker than 

 the other. Multiplication resembles the budding of yeasts. Growth 

 takes place on nitrate agar, and on agar with soil extract and am- 

 monium phosphate, hkewise on nitrate agar. Organic nitrogen un- 

 suited, and carbon compounds also interfere. The authors believe 



