Figure 3.

Membranous material (m) with adhering Gram-negative bacteria (b) comparable to those on the surface of the Mixotricha and other protist genera (such as those in Fig. 2 Inset). Cytoplasmic tubule is visible in cross section in bacterium labeled b. The sections of all epibionts are transverse except that at the arrowhead at the upper right, which is longitudinal. (Bar = 1.5 μm.) (Inset A) Karyomastigont (k) nucleus (n) in amber similar to that of live Mixotricha; w, wood. (Bar = 0.5 μm.) (Inset B) Protist nucleus (n) with intact membranes not associated with a mastigont. (Bar = 1.0 μm.) (Inset C) Karyomastigont nucleus (n) at arrow, with membrane (m). (Bar = 2 μm.) (Inset D) Bacterial endospore similar to those produced by the extant termite bacillus Arthromitus. (Bar = 0.4 μm.) Images were produced by transmission electron microscopy.