STUDIES IN ARTIFICIAL PARTHENOGENESIS. III. CORTICAL CHANGE AND THE INITIATION OF MATURATION IN THE EGG OF CUMINGIA

Abstract

1. The Cumingia egg is surrounded by a stiff vitelline membrane which tightly encloses the fluid cytoplasm. 2. A release from the restraint of this membrane is followed by maturation. 3. Such a release from restraint can be accomplished in three ways; by membrane elevation, by membrane swelling, or by the removal or rupture of the membrane. 4. Substances which themselves have low surface tension produce a lowered surface tension of the membrane and this results in its elevation from the egg surface. 5. Acids, alkalies, and certain salt solutions cause the vitelline membrane to swell. 6. The membrane may be removed from the eggs by shaking, or it may be caused to rupture by immersion in dilute sea-water. 7. All of the above mentioned treatments produce polar-body formation. All of them free the egg from restraint. 8. Maturation in Cumingia is not dependent on an increase in oxidations. 9. Cortical change in Cumingia produces no increase in permeability either to dissolved substances or to water. 10. The essential features of cortical change in Cumingia are the same as those previously shown for Arbacia.