Eight morphological variants, the product of colonial dissociation, were isolated from cultures of the marine pseudomonad B-16. Features which distinguished the variants were smooth versus rough colony type, the presence or absence of color, and differences in colony diameter. The variants differed in their capacity to form stable protoplasts and to grow at suboptimal Na+ concentrations in defined medium. All, however, required Na+ for growth. The ability of the organism to accumulate α-aminoisobutyric acid (AIB) and the requirement for Na+ for this process was not affected by dissociation.