The Physical State of Protoplasm with Special Reference to Its Surface

Abstract

Interdependence of nucleus, cytoplasm and protoplasmic surface film is stressed and evidence presented for the existence, at least in Echinoderm eggs, of a protoplasmic surface film, as a water insoluble, flowing film-like membrane which is normally supported, on the inside, by a granular plasma-gel layer and on the outside by extraneous, protein-like cuticles. The structure which alone maintains the integrity of the protoplasm is the protoplasmic surface film lying between. Ca in the environment stiffens the extraneous coats but enhances the stabiJity and fluid nature of the protoplasmic surface film and coagulates the plasma-gel layer wherever the film is ruptured. In repair the coagulum probably serves as an interface where the surface-active material may accumulate to form itself into a protecting protoplasmic surface film.