STRATIFICATION AND BREAKING OF THE ARBACIA PUNCTULATA EGG WHEN CENTRIFUGED IN SINGLE SALT SOLUTIONS

¹ Marine Biological Laboratory, Woods Hole, and the Biological Laboratory, Princeton University

When unfertilized Arbacia punctulata eggs are centrifuged in isosmotic single salt solutions, they stratify with decreasing readiness (indicating increasing viscosity) in the following order: CaCl₂ > MgCl₂ > S.W. > NaCl > KCl. They break into "halves" with decreasing ease in the reverse order, those in CaCl₂ which stratify best, break least readily. In the bivalent salts they stratify better and break less readily than in sea water, and in the monovalent salts they stratify less and break more readily than in sea water. The ease of breaking must be determined by an effect of the salts on the surface layers rather than by their effect on the interior viscosity.