148 ELECTRON-MICROSCOPIC STRUCTURE OF PROTOZOA 



but in the dried specimens may become detached. Grimstone 

 (1961) has published a micrograph of a section of termite 

 Trichomonas showing a distinct fold of the cell surface, with the 

 flagellum, surrounded by its own membrane, adhering to one 

 side of the fold. The flagellar membrane is greatly expanded and 

 encloses what appear to be several sheets of fine filaments. It 

 appears that the undulating membrane of the termite Trichomonas 

 includes a true membrane contributed by the cell surface, while 

 that of Tritrichomonas is merely an inflated and reinforced flagellum 

 without intimate connection to the cell. 



The axostyle of Tritrichomonas is a tubular structure, limited by 

 a sheet of fine (14 m/z) fibrils and filled with spheroidal granules 

 of varying size and moderate density (Fig. 55, PL XIV). 

 Anteriorly, the surface of the axostyle facing the nucleus appears 

 to be interrupted, so that its cavity is open to the cytoplasm. At 

 the cell apex, the tip of the organelle extends around the kineto- 

 somal complex without making any direct contact with it. At 

 the posterior end of the cell, the structure identified by light 

 microscopists as a chromatic ring encircling the axostyle is seen 

 as a cluster of paired granular membranes. Where it protrudes 

 from the posterior end of the cell, the tip of the axostyle is covered 

 by an extension of the cell membrane. 



The cytoplasm of Tritrichomonas contains an abundance of 

 Palade granules, scattered granular membranes, and numerous 

 very small vesicles. In addition, ovoid bodies called chromatic 

 granules by light microscopists are distributed through the cell 

 but are particularly conspicuous aligned alongside the costa. 

 These are limited by double membranes and contain a rather 

 densely granular material. Other bodies of similar size are identified 

 by Anderson and Beams as mitochondria; their internal mem- 

 branes are indistinct. Inoki and his colleagues (1959) were unable 

 to find mitochondria in Trichomonas vaginalis. The nucleus in 

 Anderson and Beams' micrographs is rather uniformly dense, 

 with more compact zones constituting the nucleoli. Surrounding 

 the annulate double envelope is a layer of circumferentially 

 oriented granular membranes. 



A single micrograph of the trichomonad flagellate Foaina 

 (Grasse, 1956b) shows a number of structures of interest (Fig. 57, 

 PL XV). Four kinetosomes lie close together, and just behind 



