PROTOPLASMIC MOVEMENT IN THE FORAMINIFERAN, ALLOGROMIA LATICOLLARIS; AND A THEORY OF ITS MECHANISM

Abstract

1. Protoplasmic streaming in the reticulopodia of Allogromia laticollaris is described. Streaming is always a two-directional movement of two threads of plasmagel which together with attached granules seem to make up the entire structure of the reticulopodia. There is no outer tube of gel, no central core of optically refractive material, and no space for an outer hyaline layer. This seems to be the simplest form of filament streaming known to exist. 2. It is proposed that the mechanism of filament streaming in Allogromia consists of active shearing or parallel displacement forces located between the adjacent surfaces of the two gel filaments, acting longitudinally and oppositely from one filament to the other so as to produce two-way streaming. 3. Possible applications of the theory of active shearing forces to protoplasmic movement in other materials are discussed. 4. It is suggested that in Allogromia the gel threads of the reticulopodia may not be covered by a typical cell membrane but by a surface precipitation membrane or that the membrane may be merely the surface of the gel filament itself. 5. The possible taxonomic significance of the existence of two major types of protoplasmic movements, namely, pressure flow and filament streaming, is discussed.