The form resistance of chitan fibres attached to the cells ofThalassiosira fluviatilisHustedt

Abstract
When the cells of Thalassiosira fluviatilis Hustedt are incubated in chitinase their chitan fibres are removed. Chitinase-treated cells sank more than 1·7 times faster than control cells with attached fibres. A method of determining the density of algal cells is described. The cells of T. fluviatilis have a density of 1·121 g cm-3, which is less than that of the chitan fibres (1·495 g cm-3). The fibres must therefore decrease the cell sinking velocity by increasing form resistance. It is calculated that the fibres increase the cell form resistance by a factor of more than 1·9, and increase the overall surface area of the cell by a factor of up to 2·8.
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