No morphological difference was revealed by electron microscopy between or among different strains of phage ε15 which were obtained from S. newington, S. selandia, S. newbrunswick, S. cambridge and S. kinshasa of group E2, and S. canoga, S. illinois and S. thomasville of group E3. The sperm-shaped particles of phage ε15 have a spherical head (54-58mμ in diameter) with an elongated tail (20×162-186mμ).
