PROTOPLASMIC VISCOSITY CHANGES DURING MITOSIS IN THE EGG OF CHAETOPTERUS

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Abstract
Using the centrifuge method, protoplasmic viscosity detns. were made at 1-min. intervals during the period between fertilization and cleavage. These changes were correlated with the course of the mitotic processes in the egg, as detd. by a minute-to-minute study of fixed, sectioned and stained material. During the cleavage mitosis, marked changes in protoplasmic viscosity occur. The appearance of the mitotic spindle is preceded by an increase in protoplasmic viscosity and is followed by a decrease in protoplasmic viscosity. During the metaphase, the viscosity of the protoplasm is low; it rises just before the cell divides. The results obtained are consistent with earlier observations made with standard methods on other marine eggs.