Scale formation in chrysophycean algae

Summary The two types of scales of the coccolithophorid Hymenomonas (= Cricosphaera) carterae have been studied with the negative staining technique. Both types of scales, including the non-mineralized circular ones and the larger, mineralized elliptical ones are made up of a highly ordered network of radial and concentric fibrils. Both fibrils are ribbon shaped and have dimensions of 10–22×30–75 Å in cross-sections. The margin of the scales is composed of two closely associated fibrillar ribbons which are observed occasionally in edge view. In the elliptical scales, the periphery of the fibrillar network often is obscured by a deposition of the coccolith calcium carbonate. The substructure of the fibrils, the occurrence of kinking sites, and the fibrillar resistance to alkaline and weak acid treatments strongly resemble the scales of Pleurochrysis scherffelii. In relation to the recent findings of Brown and co-workers (Brown et al., 1969, 1970) on scale formation processes, it is hypothesized that the fibrillar network of the scales of both species is structurally and chemically identical, and that the fibrillar material consists of a cellulose-like polysaccharide.Supported by the Deutsche Forschungsgemeinschaft (to W. W. F.) and NSF Grant # GB 23047 (to R. M. B.).