On Allen's suggestion for long-distance translocation in phloem of plants

Abstract

N. S. ALLEN has made a film of the streaming of cytoplasm in Nitella, in which she used laser light through chloroplast-free ‘windows’ in the walls of the giant alga cell to take a cine film under Nomarski optics. This film shows that the cytoplasm, which seems to flow steadily and spirally along the axis of the cell, contains undulating filaments that apparently provide the motive force for streaming. It is postulated¹ that endoplasmic filaments undulate in a sinusoidal fashion and thereby drive the cytoplasm. There is some supporting evidence that these filaments are branches originating from microfilament bundles which in turn are normally anchored and parallel to the fixed chloroplast rows. The waves passing along the semi-free microfilament branches cause them to act somewhat like beating flagella in other organisms.