Tension At The Surface of Sea-Urchin Egg: A Critical Examination Of Cole’s Experiment

Abstract

ABSTRACT The sea-urchin egg can be deformed by external force, and on removing the force it tends to round up. Assuming that the inner protoplasm is liquid, such a return to sphericity must be due to a force working at or near the surface of the egg. The surface force, or the tension at the surface, as referred to by Harvey, has been measured by several methods (Vlès, 1926; Harvey, 1931; Cole, 1932; Cole & Michaelis, 1932; Sichel & Burton, 1936; Norris, 1939). Most of them were reviewed by Harvey & Danielli (1938). Among these workers, however, Cole alone provided information which has been accepted as a proof that the cortex is elastic.