GENERAL SYSTEMATIC BACTERIOLOGY 443 



have not used this name. It may be regarded as a synonym of Rhizo- 

 hium. 



Rhizobium. A generic name proposed by Frank (1889, p. 338) 

 to include the organisms causing the formation of nodules on the roots 

 of leguminous plants. He expresses the belief that the organism proba- 

 bly belongs to the fission fungi or bacteria and states: 



Um in der vielleicht noch sich aufwerfenden Discussion, ober zu den Myxomy- 

 ceten oder zu den Spaltpilzen, sei, in der Namengebung nichts zu prajudiciren, 

 ist vielliecht die Beziechnung Rhizobium legtiminosarum fiir ihn empfehlenswerth. 



This generic name has been used by several authors, among them 

 Ludwig (1892, p. 99) Schneider (1892, p. 203) and Hiltner and Stormer 

 (1903, p. 151). 



The name is rejected by Erwin F. Smith (1905, p. 174). Orla- 

 Jensen (1909, p. 334) proposed the substitution of the name Rhizo- 

 monas. 



Winslow et at. (Committee Soc. Am. Bact., 1917, p. 553) make the 

 following statement. 



Phytomyxa Schrotei has priority over Rhizobium, but because of the confusion 

 which would arise from the substitution of the older correct name for the better 

 known term Rhizobium, the committee recommends the adoption of the latter. 



Minute rods, motile when young by means of polar flagella. Involution forms 

 abundant and characteristic when grown under suitable conditions. Obligate 

 aerobes, capable of fixing atmospheric nitrogen when grown in the presence of 

 carbohydrates in the absence of compounds of nitrogen. Produce nodules upon 

 the roots of leguminous plants. 



The type species is Rhizobium leguminosarum Frank. 



Buchanan (1918, p. 46) gave the following description. 



Rod-shaped cells, motile when young by means of polar flagella, obligate 

 aerobes, fixing atmospheric nitrogen when grown in a nitrogen-free medium con- 

 taining suitable carbohydrates, involution forms abundant and characteristic, 

 usually growing in the nodules of the roots of leguminous plants. 



The type species is Rhizobium legurninosarum Frank. 



The name of this genus has been a source of confusion. The organism of legu- 

 minous nodules was placed in the mold genus Schinzia by Frank as Schinzia 

 leguminosarum. Schroeter (1886, p. 134) concluded the organism to be one of the 

 slime molds and created the genus Phytomyxa, including it in the order Phyto- 

 myxini among the Myxomycetes. He based his conclusions as to the position of 

 this organism among the slime molds upon the work of Prilleaux (1879, p. 98). 

 Beijerinck (1888, p. 758), named the organism Bacillus radicicola. Frank (1889, p. 

 338) renamed the organism Rhizobium leguminosarum. The fact that Schroter 

 included this genus incorrectly among the slime molds does not invalidate the 



