402 J.J. PATEI~: Phage-Like Particles from a Lysogenic Thermomonospora magnification of 40,000. These showed tadpole-shaped particles ( Fig. 1) with a symmetrical icosahedral head measuring 68 my, across. The tail, which lacked a contractile sheath, measured 125 my. in length and 8 m~ in width. The particles have wider head than the phages for Thermoactinomyces vulgaris and longer taiI (PATEL, 1969), and in morphology they differed also from the phage-like particles isolated from Escherichia coli and Pseudomonas aeruginosa (BI~ADL:Eu and DEWAR, 1966 CRoss, T., and J. LAcEY: Studies on the genus Thermomonospora.