Though the accommodation of bacteria of the B. globiforme group in a separate genus, as proposed by Conn and Dimmick, has much to commend it, the matter of specific distinction within the proposed genus, Arthrobacter, is a problem which requires wider surveys than have been reported, classification of the chromogenic forms related to B. globiforme appearing to merit special attention. Though these have been encountered rarely by some investigators they are quite common in soil. They appear, however, to be largely associated with the growing plant. In a study of the effect of plant growth on the soil bacterial flora, no chromogenic cultures of the B. globiforme group were obtained from the control soils, whereas 42.3% of all strains of this group isolated from soil adhering to the roots were yellow forms.