A "NORMAL" DEVELOPMENT OF DENUDED EGGS OF THE STARFISH, ASTERINA PECTINIFERA*

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Abstract
Experimental conditions that allow normal development of starfish eggs stripped of the fertilization membrane are reported. Four kinds of intercellular relationships are distinguished during the pre-hatching stages. Cells at the 2-8 cell stages are hardly related to each other, while those from 16-128 cell stages are bound loosely together. After the 8th division (.apprx. 5.5 h after insemination at 21.degree. C) cells adhere closely and cooperate with each other to perform morphogenetic movement of blastulation. This is replaced by that of a true multicellular system at .apprx. 10 h after insemination. Soon after this, ciliary action carries the embryo away from the substratum.