VISCOSITY CHANGES IN AGEING UNFERTILIZED EGGS OF ARBACIA PUNCTULATA

¹ From the College of the City of New York

1. Relative viscosity was determined by (a) change in percentage of eggs zoned to a fixed standard, at constant centrifugal force and time; (b) change in time at a given force to produce same percentage of equally zoned eggs.

2. Ageing unfertilized eggs manifested five major phases in viscosity, viz.

(a) Unripe eggs. No trace of zoning could be induced. They were at least eleven times more viscous than mature eggs.

(b) All mature eggs were readily zoned at much lower forces and duration. Maturation is accompanied by profound and apparently rapid liquefaction.

(c) During the first ca. 35 hours after shedding, ripe eggs progressively increased in viscosity, 2 to 3 x. At constant force and time, the zoned eggs decreased with age from 85 to 0 per cent. To produce the same percentage of equally zoned eggs, the centrifuging time increased from ca. 2 to 5 minutes. Similar results were obtained when eggs were centrifuged in isosmotic sugar solution.

(d) With further ageing, viscosity was reversed. There was progressive liquefaction. The decrease was 3 to 4 x.

(e) Upon death viscosity was again sharply increased at least eleven times.

3. The amount of change with age is greater than that during mitosis, or induced by heat, acid, light, etc.

4. Temperature and acid are excluded as factors in the cyclical viscosity changes with age.

5. Perivisceral fluid is also not responsible.

6. Increasing permeability to water is associated with increasing viscosity during early and intermediate ages. During late ages, with excess water intake, viscosity is reversed.

7. Viscosity increased during early ages with no detectable injury. It increased further with progressive injury, i.e., during intermediate ages. w25It decreased during the period of most rapid injury.