Plate III. Electron micrographs of sections of some flagella. 



(a) Transverse sections through the tips of flagella of 

 Pseiidotrichonympha and Trichonympha. The series shows the 

 successive reduction in size of the flagellum and the reduction 

 in number of internal fibrils, x 100,000. 



{b) Longitudinal section through the basal body and proximal 

 part of the flagellum of Holomastigotoides. The flagellar shaft 

 is closely applied to the body surface at the left (towards the 

 posterior end of the animal), but not to the right, showing that 

 the insertion of the flagellum is at an acute angle to the body 

 surface. In the shaft the central and peripheral fibrils can be 

 seen, and in the base the three subfibrils of a triplet are visible 

 on the left, while on the right the fibrous ribbon shown in 

 Plate XII la is seen in section at the side of another peripheral 

 fibril. > 75,000. 



All micrographs are from Gibbons and Grimstone (1960). 



