Electron Microscope Observations on the Zoospores of Pylaiella and Laminaria

The zoospores of Laminaria saccharina and Pylaiella litoralis have both been shown to possess a hairy front flagellum (Flimmergeissel). In both cases this is longer than the smooth hind flagellum. There is no proboscis. In Pylaiella it has been shown that the hairs are in two rows on the front flagellum and that they arise in pairs except at the extreme front end. Each hair has a jointed structure and consists of a thicker basal portion which passes abruptly into a thin distal portion. There are signs of a loose transparent skin covering the axis of the flagellum between the rows of hairs. The axis has also been shown to be fibrillar in construction and to be capable of decomposing into eleven strands, two of which are central. There is perhaps an intercalary material in the axis in addition to the component fibrils.