72 STRUCTURE 



Tritrichomonas carries three free anterior flagella and one 

 recurrent flagellum which runs along the outer margin of the 

 undulating membrane (Fig. 16). All four flagella arise in a 

 blepharoplast region, in which Anderson and Beams (1959, 1961) 

 found four normal basal bodies. From the base of the recurrent 

 flagellum arises the costa, a coarse fibre about 0-4 ft in thickness 

 which runs most of the length of the body and has obvious striations 

 (period about 500 A). A shorter and rather narrower striated fibre 

 called the parabasal filament runs backwards from the basal body 

 of an anterior flagellum to end just posterior to the nucleus. Both 

 of these are probably supporting structures. A third large structure 

 in this flagellate is the axostyle, a hyaline rod extending the length 

 of the animal from near the blepharoplast complex to the posterior 

 end; this may have a skeletal or contractile function. 



The bases of the four or eight flagella of Pyrsonympha lie in the 

 blepharoplast region at the anterior end of the body. A thick 



Fig. 17. Tentative diagram of the fine filament system in and 



around the proximal part of the basal bodies of flagella of 



Trichonympha (from Gibbons and Grimstone, 1960). 



ribbon runs backwards from the blepharoplast-complex as a 

 hook-shaped structure, and gives attachment to a very large 

 number of tubular fibrils which are grouped to form the axostyle. 

 In transverse section the axostyle shows a structure reminiscent 

 of a " kinetodesma " of Stentory since the fibrils are of similar 

 appearance and dimensions, and are arranged in lamellae, 14 to 74 

 of which were found stacked together. Grasse (1956), who carried 

 out this study, also noticed that the axostyle was contractile, and 



