Microscopical Observations on Achnanthes subsessilis, with Particular Reference to Stalk Formation

Abstract

The general arrangement of cytoplasmic organelles in A. subsessilis is similar to that of other pennate diatoms. The central nucleus is surrounded by perinuclear Golgi bodies which may produce vesicles containing stalk material. The stalk is composed of 4 layers, is secreted from the raphe and in this region is surrounded by a mucilaginous collar. At the point of attachment the stalk spreads out over the surface and the outer layer terminates. The stalk is composed of polysaccharide without any associated protein and the center is more sulfated than the periphery. The stalk raises the cell well above the boundary layer on an antifouling-treated surface, permitting its continued growth and multiplication. [The success of this diatom as a fouling organism was discussed.].