70 STRUCTURE 



similar Pedinomonas, four fibrils run out to the cell surface and the 

 plastid (Manton and Parke, 1960). Striated rootlets run from each 

 flagellar base of the biflagellate alga Synura to ramify over the 

 surface of the nucleus, while, in addition, non-striated fibrils run 

 out in the direction of the cell surface (Manton, 1955). 



Rather similar rootlet arrangements are found in the zoospores 

 and spermatozoids of the larger algae. In the green algae, the 

 basal bodies of the quadriflagellate zoospore of Draparnaldia are 

 linked by a ring of fibrils, and four rootlets bearing faint striations 

 were found to leave the fibril ring at points equidistant from the 

 nearest flagella and run to various parts of the cell (Manton, 

 Clarke and Greenwood, 1955). The structure of the biflagellate 

 spermatozoid of the brown alga Fucus is complicated by the 

 presence of a pe-^aliar probosics (PI. IXa) whose detailed structure 

 was described by Manton and Clarke (1956). Here the two basal 

 bodies lie side by side at almost 180° to one another. From the 

 region of the basal bodies, 13 fine fibrils run forward in a group 

 away from the body of the cell, they then loop back to the surface 

 and continue to the posterior part of the cell where they end. In 

 the anterior loop, all the fibrils lie in the same plane to form the 

 flat proboscis. Two shorter fibrils leave the region of the basal 

 bodies; one runs direct to the eye-spot, while the other runs out 

 over the surface of the proboscis. 



The spermatozoid of the fern Pteridium is more complex, for 

 it carries many flagella. Manton (1959b) found that the spiral 

 backbone of the spermatozoid is a broad fibrous band, built up 

 of many fibrils about 200 A in diameter, which is associated with 

 the nucleus and a spiral of modified mitochondria. Dense material 

 around the basal bodies of the flagella runs along the fibrous band, 

 so that the flagella are connected to the main skeletal structure 

 of the cell. Complexity of organization is carried further in the 

 cycad sperm, where Barton (1962) has found that some 25,000 

 flagella are arranged in a spiral tract which is underlain by a broad 

 fibrous band. Within this band three layers of fibres could be 

 recognized, the outermost of which is associated with a layer of 

 dense material around the proximal ends of the basal bodies. 



The uniflagellate Trypanosoma (Anderson, Saxe and Beams, 

 1956), Leishmariia (Pyne, 1958; Pyne and Chakraborty, 1958) 

 and Blastocrithidia, (Vickerman, 1962) and the biflagellate 



