554 Journal of Agricultural Research vol. xx.No. 7 



(2) The first group shows all features characteristic of Bacillus radi- 

 cicola Beijerinck. It is peritrichic, grows relatively fast on agar plates, 

 and changes the milk in a very characteristic manner. It produces 

 nodules on the roots of the following plants: clover, sweet clover, alfalfa, 

 vetch, pea, navy bean, lupine, black locust, Amorpha, and Strophostyles. 



(3) The second group is characterized by monotrichic flagellation, 

 comparatively very slow growth on agar plates, and inability to cause a 

 marked change in milk. It has been isolated from cowpea, soybean, 

 peanut, beggarweed, Acacia, Genista, and Cassia. 



(4) According to the customary manner of classifying bacteria, this 

 second group of nodule bacteria would have to be considered to be a new 

 species, and according to the rules of priority, it would have to be named 

 Pseudomonas japonica or Bacterium japonicum (Kirchner). But we do 

 not advocate such a procedure, because only a complete study of the life 

 history of these two groups of organisms would make it possible to say 

 definitely whether they are, indeed, two distinct species or merely differ- 

 ent types of growth of the same organism. 



(5) Bacillus radicicola is closely related to B. radiobacter. The generic 

 name Rhizobium is to be rejected. The correct systematic position of 

 both species is in the neighborhood of B. aerogenes and B. coli. 



(6) Bacillus radiobacter seems to be regularly present in the root 

 nodules of leguminous plants, stimulating development and activity 

 of the nodule bacteria. On account of its similarity to B. radicicola, 

 it has been repeatedly mistaken for the nodule-producing organism in 

 the cowpea-soybean group, whose bacteria it outranks very considerably 

 in the development on the plates made from the nodules. By its brown 

 growth on potato, B. radiobacter can be easily differentiated from B. 

 radicicola. 



LITERATURE CITED 



(1) Allen, E. R. 



1919. SOME CONDITIONS AFFECTING THE GROWTH AND ACTIVITIES OF AZOTO- 



bacter chroococcum. In Ann. Mo. Bot. Gard., v. 6, no. 1, p. 1-44, 

 1 pi. Bibliography, p. 42-43. 



(2) Barthel, Chr. 



1917. die geisseln des bacterium radicicola (beij). In Ztschr. Garungs- 

 physiol., Bd. 6, No. 1, p. 13-17. 



(3) 



1919. cultures de bacteries sur terre sterilisee. In Meddel. K. Vetensk. 

 Nobelinstitut, bd. 5, no. 2, 13 p., 1 pi. 



(4) Beijerinck, M. W. 



1888. DIE BACTERIEN DER papilionacEEN KNOLLCHEN. In Bot. Ztg., Jahrg. 

 46, No. 46, p. 725-735, pi. 11; No. 47, p. 741-750; No - 48, p. 757-77 1 ; 

 No. 49, p. 781-790; No. 50, p. 797-804. 



(5) and van Delden, A. 



1902. UEBER DIE assimilation des freien STICKSTOFFS durch BAKTERIEN. 

 In Centbl. Bakt. [etc.], Abt. 2, Bd. 9, No. 1/2, p. 1-43. 



