ZOOFLAGELLATES 147 



According to Anderson and Beams' accounts (1959, 1961), 

 which provide the clearest micrographs of sectioned cells, the 

 kinetosomes of all flagella are conventional hollow cylinders 

 (Fig. 56, PL XV) formed by the nine fibrils that continue into 

 the flagellum. Small dark granules occupy the centers of the 

 kinetosomes, and a finely granular, rather dense matrix surrounds 

 the whole cluster, but no separate identifiable centriole is 

 detectable. That the matrix of the centroblepharoplast area has 

 properties distinguishing it from the surrounding cytoplasm is 

 apparent from its staining reactions and also from observations 

 on fragmented cells. When termite-inhabiting Trichomonas is 

 fragmented by ultrasonic bombardment (Pitelka, unpublished), 

 a frequent component of the resulting brei is a mastigont lacking 

 only the axostyle: flagella, costa, and parabasal filament are all 

 present, diverging from a dense, bulbous central body. 



The costa is a stout, striated rod that originates in contact with 

 the kinetosome of the recurrent flagellum; its repeating pattern 

 consists of subdivided light and dark bands at intervals usually 

 under 60 m/x but varying in different regions of the same organelle. 

 The parabasal filament is similar but much slenderer, and arises 

 from the kinetosome of one of the anterior flagella. The Inoki 

 group (1961) considers that the costa in Trichomonas foetus is a flat 

 band at the cell surface, directly along the line of attachment of 

 the undulating membrane. A heavy striated, rod equivalent to 

 the structure identified by other authors as the costa is also present. 



Anderson and Beams found that the undulating membrane of 

 Tritrichomonas maris consists of an expanded flagellar sheath 

 enclosing, in addition to the fibrous flagellar axis, one or two 

 dense granular strips believed to correspond to the "accessory 

 filament" of light microscopy, and a finely fibrous sheet-like 

 component. The site of adhesion of the membrane to the body 

 surface is marked only by a homogeneous or finely filamentous 

 substance of low density occupying a gap between the adjacent 

 membranes. Perhaps the undulating membrane differs in 

 structure in different species. Electron micrographs of whole 

 cells of Trichomonas from a termite gut (Fig. 54, PI. XIV) show 

 a broad undulating membrane consisting of a finely fibrillar sheet 

 bordered by a homogeneous band (Pitelka, unpublished). The 

 recurrent flagellum normally follows the inner edge of this band, 



