Transmission Electron Micrograph (TEM) of endonuclear bacteria. Nucleus showing nuclear envelope, chromosomes, nucleoplasm and bacteria in the euglenoid Trachelomonas; the endonuclear bacteria cluster around the central nucleolus; the cytoplasmic bacteria lie among the ribosomes, mitochondria and Golgi bodies; all the bacteria are encapsulated but do not fix nitrogen and do not appear to form a symbiotic or parasitic relationship with the host cell; they have apparently acquired an unusual ecological nice without aiding or harming the host (though they must be withdrawing nutrients) and divide to keep pace with host cell nuclear division; EM section. Magnification: 30,000X at 6x7" print size.