ELECTRON MICROSCOPE OBSERVATIONS OF DIATOMS

1. Three-dimensional carbon replicas can be used to study frustular morphology with greater accuracy than either regular carbon replicas or nonreplicated frustules. Because of their resemblance to thru-focus drawings, carbon replicas are well-suited for taxonomic work, much more so than either light or electron micrographs of frustules. 2. Stephanodiscus hantzschiiGrun. has short spines paired with some of the long curved radial spines projecting from the valve margin. 3. Azure B staining of freshly collected diatoms may reveal the presence of tiny epiphytic bacteria on either the frustule or on extracellular polysaccharide structures which can later be detected by electron microscope examination of whole mounts. These epiphytic bacteria may derive part of their nutritional support by local digestion of diatom extracellular polysaccharides, while the bacteria in turn may provide organic nutrients required by their diatom host. 4. The variety of techniques now available enable one to conveniently use the electron microscope to answer most questions concerninig diatom structure. © 1969 Springer-Verlag.