title: The biology and ultrastructure of the testate amoeba, Difflugia lucida penard (Protozoa, Rhizopoda).
abstract: Two strains and one population of Difflugia lucida have been studied, from Germany and Japan. The ultrastructure is described from selectively cultured specimens with thin shells; such agglutinate shells have a slightly different morphology from those provided with ample mineral grains. The cytoplasm is described and of particular interest are details of the 'ovular' nucleus, which has an additional lamina to the nuclear membrane, several nucleoli and changes its position within the region of dense endoplasmic reticulum. Two types of organic cement vesicles are secreted by the dictyosomes. The building blocks are spherical in the cytoplasm but when discharged often become elongate strips. Smaller cement vesicles discharge fibrous material which is used either to line the inner shell wall or possibly form the enclosing membrane of cysts. Some cytoplasmic differences associated with the first stage of division and precystic organisation are included. Comparisons are made with recent light microscope observations.
authors.affiliation: Department of Zoology, The Natural History Museum, London, UK.
authors.forename: C G
authors.initials: CG
authors.lastname: Ogden
authors.forename: R
authors.initials: R
authors.lastname: Meisterfeld