VARIATIONS IN SHAFT STRUCTURE — FLAGELLA 39 



additional intraflagellar material of Blastocrithidia was striated or 

 perhaps hexagonally cross-linked (PI. Vllf). 



The anterior flagella of the spermatozoids of some of the brown 

 algae bear stout spines on one of the peripheral fibrils. In 

 Himanthalia there is a single large spine 1 /x long near the distal 

 end of the flagellum (PL IXb,c), while the flagellum of Dictyota 

 bears about 12 smaller spines spaced at more or less equal intervals 

 along one fibril (Manton, Clark and Greenwood, 1953). Manton 

 (1956, 1959c) believes that the spines are borne on fibril number 1, 

 the fibril that lies in the plane of bilateral symmetry. The function 

 of these spines is uncertain, though they may be used in fertiliza- 

 tion as Manton suggests. 



Additional internal material is present between the fibril bundle 

 and the membrane in shafts of a number of flagella. A thick 

 tapered strand of intraflagellar material, up to 0*5 /x in 

 diameter near the base, runs alongside the fibril bundle in the 

 flagella of Euglena and Peranema (PL VIIa,b) (Roth, 1958a, 1959). 

 No definite information is available about the structure of this 

 material, though in some cases it is fibrillar and Roth found it to 

 originate from a kinetosome-like body, so that it may be compar- 

 able with the material of the fin of amphibian sperm (p. 42). 

 Incidentally, the basal 1 ju, of the flagella of Euglena and Peranema 

 were found by the same author to lack the central fibrils of the 

 fibril bundle, which is in this region swollen to about twice its 

 normal diameter (at least in fixed preparations). The central 

 fibrils are also lacking in the basal region of trypanosome flagella. 

 where there may be a complex transition region (PL XI Ic and d). 



Intrafl.agellar material in Pyrsonympha, where the 4 to 8 flagella 

 run in spiral grooves along the surface of the animal, takes the form 

 of peripheral dense strands, usually triangular in section, opposite 

 some of the peripheral fibril doublets (PL Vile) (Grasse, 1956). 

 The flagella seem to adhere in the grooves in some way, and may 

 have attachments similar to those of the proximal parts of flagella 

 of Pseudotrichonynipha to the walls of grooves on the body. 



The flagellar bases of Pseudotrichonynipha occur in rows at the 

 bottom of longitudinal grooves, and there are connexions between 

 the flagella and the walls of the groove, and also occasionally 

 between adjacent flagella (Gibbons and Grimstone, 1960). These 

 connexions are reminiscent of the compartmenting lamellae in 



