Taxonomic Relationships of Alcaligenes spp. to Certain Soil Saprophytes and Plant Parasites.

Recently one of the writers (Conn, 1938) proposed the name Rhizobiaceae for a family containing the genera Rhizobium, Alcaligenes, and Chromobacterium, together with certain species commonly placed today in the genus Phytomona8. This suggestion has been followed in the 5th edition of Bergey's Manual of Determinative Bacteriology. Inasmuch as the writer's paper above mentioned was published only in abstract form, it seems wise to present in greater detail the data on the basis of which the suggestion was made. Some 35 years ago (Conn, 1913), interest was expressed in a group of non-spore-forming rods, which are very abundant in soil, which are usually gram-negative and slow liquefiers of gelatin. Various efforts have been made to classify the group and to decide to what other groups of bacteria they are related. This proved difficult because these organisms are characterized so largely by negative features. A name was given (Conn, 1928) to one organism of this group, however, (Bacterium globiforme) which is easily recognized because in its life history on agar slant cultures it changes from a gram-negative rod to a gram-positive