This work is designed to explore the molecular structure of the flagellar membrane of the phytoflagellate, Ochromonas danica. This membrane lacks phospholipids, which are present in all other biological membranes. It is made of primarily three lipid components, sulfatides, free fatty acids and sterols. The structures of all three have been established in this laboratory. The sulfolipids are primarily 1,14-docosaneudiol-1, 14-disulfate and 1,15-tetracosanediol-1,15-disulfate, together with up to six chloro groups replacing hydrogens on an otherwise saturated hydrocarbon chain. These substances have been found in all fresh water algae (over 20 species) in which they have been sought but are absent form marine algae (nearly 10 species). The membrane is constituted on completely anionic lipids. Neither organic cations nor metallic cations are present in the isolated membrane preparation. The work is designed to explore the conformations of the lipids and a hypothetical structure of the bilayer which bases its stability on protonated sulfates. NMR, X-ray, and other physical methods are being utilized for these studies.