CELL-BINDING SUBSTANCES IN SEA URCHIN EMBRYOS*

Properties of ovacquenin, a reaggregation-promoting substance from sea urchin embryos, were further studied and compared with those of hyalin, a calcium-insoluble protein of the hyaline layer surrounding the sea urchin embryo. Properties of hyalin were basically in agreement with previous reports, but differed in some aspects. Hyalin and ovacquenin were very similar in various aspects and were hard to distiguish generally, but they were separated by ammonium sulfate fractionation. Hyalin was precipitated at a low salt concentration, while ovacquenin remained soluble until the salt concentration exceeded half saturation. Therefore it was concluded that hyalin and ovacquenin are very much alike but distinct from each other. Probable relation of ovacquenin to hyalin was discussed.