PARTHENOGENETIC MEROGONY OR CLEAVAGE WITHOUT NUCLEI IN ARBACIA PUNCTULATA

Abstract

1. Non-nucleate fractions of Arbacia eggs obtained by centrifuging can be activated by parthenogenetic agents, and develop; these may be termed "parthenogenetic merogones." 2. Asters are formed and cell division takes place without nuclei. 3. Cleavages of non-nucleate fractions are strikingly similar to those of nucleate fractions (or whole eggs) of the same stage of development. 4. Many cleavages, in sequence, result in the formation of a blastula of as many as 500 cells. 5. Blastulæ emerge from the fertilization membranes; one embryo was still viable after a month.