PHYTOFLAGELLATES 125 



extraordinarily heavy anterior flagellum of Peranema trichophorum 

 has a rather scant coating of mastigonemes, but the striated bands 

 are particularly well developed. Pitelka and Schooley showed 

 that these were present as two easily detached ribbons about 

 400 m/x wide and with a transverse striping regularly repeated at 

 about 100 m/x. In Roth's (1959) micrographs of sectioned 

 flagella they appear as two curved ribbons flanking the flagellar 

 axis (Fig. 40, PL XI), each ribbon consisting of four to six layers 

 of dense, striated material. 



The following account of the ultrastructure of Euglena is 

 derived from reports by Groupe (1947), Wolken and Palade 

 (1953), Reger and Beams (1954), Wolken (1956, 1960), Roth 

 (1958a), Pitelka and Schooley (1957 and unpublished), Ueda 

 (1958), de Haller (1959, 1960), and Gibbs (1960, the latest and most 

 detailed account). All of these authors used jE. gracilis except 

 de Haller, who studied E. viridis. 



The euglenoid pellicle is marked by longitudinal spiral striations 

 that may take the form of deep grooves and crests and may be 

 elaborately sculptured. It contains no cellulose (Pigon, 1947). 

 It may be extremely plastic in some species and quite rigid in 

 others. At the anterior end of the cell is a conspicuous, flask- 

 shaped chamber, the reservoir, within which the flagella arise and 

 into which the contractile vacuoles discharge. The reservoir 

 communicates with the exterior subapically via a canal of moderate 

 width. Isolated pellicle fragments of E. gracilis examined by 

 Pitelka and Schooley (1957 and unpublished) shed some light on 

 the disposition and composition of the conspicuous striations. 

 According to Pochmann (1953, 1957) the euglenoid cell has a 

 fundamental bilateral symmetry, usually obscured by spiralization. 

 Fig. 44, PL XII, showing an empty pellicle, supports Pochmann's 

 conclusion. Lateral striae form two whorls which spiral in the 

 same sense but would be symmetrical if the spirals were straightened 

 out. Medial striae converge to enter the neck of the reservoir in 

 close-set ranks. Pochmann has shown that during division the 

 cleavage plane passes through the reservoir opening and down 

 the middle of the cell, spiraling with the striae. How bilaterality 

 is reestablished in the daughter individuals remains unexplained. 

 At the posterior pole of the cell, the striae, greatly reduced in 

 number by fusion, converge in a single whorl. 



