Nomenclature of the Root-Nodule Bacteria of the Leguminosae

edition, 1925, the root-nodule bacteria of the Leguminosae are classified in the genus Rhizobium, and two species Rh. legumino-sarum and Rh. radicicola are recognized. Differentiation be-tween the two species is established upon the basis of morphology, with particular reference to flagellation, cultural characters, and habitat of the organisms. Only incomplete descriptions of the organisms are given, which fact renders an accurate classification and identification difficult. With the exception of the habitat, no characteristic is described in sufficient detail to render identi-fication possible, and only a very limited number of host plants are mentioned under each bacterial species. In the seventh edition of Lehmann and Neumann's Bakteriol-ogische Diagnostik, 1927, the nodule bacteria of the various leguminous plants are classified as one species, Bacterium radi-cicola Beijerinck. The possibility of recognizing several sub-species or varieties is mentioned. At present both American and foreign investigators use several different names for the same organism. Scientific workers have not agreed, either as to the number of species which should be recognized, or as to the terminology which should be applied to them. To avoid confusion many have abandoned the use of scientific terminology and have substituted such terms as "root-nodule bacteria of legumes " or, when a more specific designation was desired, such terms as "alfalfa-nodule bacteria, " "soybean-nodule bacteria " or "alfalfa bacteria, " "soybean bacteria. " At