15–19. Ultrastructure of trypanosomatid flagellate Herpetomonas sp. Ind3 infecting Euplotes encysticus. 15–18. Flagellates harbored in the host cytoplasm. 15, 18. Longitudinal sections of flagellates. 16. Cross-sectioned flagellate through the flagellar pocket; the flagellum, which already bears a paraflagellar rod, is visible. Regularly distributed subpellicular microtubules are also well visible (diagonal arrow). 17. Cross section of two flagellate cells after fission. 19. Parasites in the macronucleus of the host. N, nucleus; horizontal arrow, kinetoplast; double arrows, flagellum. Bars = 1 μm.