The Structure of Protoplasm and of Inorganic Gels: an Analogy.*

SCHALEK and Szegvary, and Svedberg, have recently described remarkable instances of sudden liquefaction of inorganic colloidal gels which have a striking analogy in the collapse of the gel structure of the protoplasm of a dividing echinoderm egg when the latter is subjected to mechanical pressure. It is the purpose of this paper to call attention to this analogy. Regional Changes in Protoplasmic Consistency during Mitosis. —The fertilised echinoderm egg undergoes marked localised changes in its viscosity during mitosis, t The viscosity of the inner protoplasm, constituting the core and the greater proportion of the total volume of the mature unfertilised echinoderm egg, is roughly comparable to that of concentrated glycerine (sp. gr. 1.25). Such a consistency permits smooth though slow flowing of the protoplasm out of a ruptured egg. The consistency of .the peripheral protoplasm of the egg, forming a cortical layer which encloses the core, is that of a soft jelly. The difference in consistency of the inner and the peripheral protoplasm of the unfertilised echinoderm egg was first pointed out by Chambers whose results were based on microdissection. These results have been confirmed by the writer by an electro-magnetic method of determining viscosity (and elasticity) values of sols, gels, and protoplasm. The method was developed by Freundlich and Seifriz. As applied to