STRUCTURAL CHARACTERIZATION OF EUTREPTIA-PERTYI (EUGLENOPHYTA) .1. GENERAL DESCRIPTION

The biflagellate cells of the photosynthetic marine euglenoid Eutreptia pertyi Pringsheim (Euglenophyta) have almost equal-length, heterodynamic flagella that emerge from the subapical opening of a tubular canal/reservoir cavity. In addition to the 9 + 2 axonemal microtubules, both flagella contain filaments that form a basket-weave paraxial rod, but the arrangement of long and short nontubular mastigonemes is different on each flagellum. A pyrenoid centre, surrounded by paramylon granules, occupies an anterio-median position in the cell, and 25-30 ribbon-shaped chloroplasts radiate from the periphery of this complex. Certain cytoplasmic vesicles, here termed 'mastigoneme vesicles', are reported for the first time in the Euglenophyta, and may contain precursors or fully-formed mastigonemes; the fibrillar contents are extruded by exocytosis into the lumen of the reservoir, where they are presumably assembled and deposited on to the flagellar surface.