Manion, R. E. (Veterans Administration Hospital, Minneapolis, Minn.), S. G. Bradley, H. H. Zinneman, and W. H. Hall. Interrelationships among mycobacteria and nocardiae. J. Bacteriol. 87:1056–1859. 1964.—A total of 134 strains of mycobacteria and nocardiae were tested for susceptibility of 24 mycobacteriophages. On the basis of capability of diverse strains to serve as alternative propagating hosts for particular viruses, relationships among the actinomycetes were proposed. Cultures received as Mycobacterium smegmatis, M. ranae, M. butyricum, and M. chelonei were nearly identical, indicating that they are members of a single taxon. M. phlei and M. fortuitum strains constituted two distinct but related groups. Moreover, strains of M. smegmatis and Nocardia asteroides were susceptible to two variant actinophages originally isolated on N. brasiliensis.