Water Balance in the Eggs of the Atlantic Salmon Salmo Salar

The rate of exchange of tritiated water across the vitelline membrane of the eggs of the Atlantic salmon has been examined under various conditions. In eggs shed into isosmotic saline the rate constant of exchange is about 0·3−0·4/hr. When eggs are shed into distilled water or isosmotic glucose rate constants as high as 0·8−1·0/hr. occur for short periods but the rate of exchange declines rapidly. Low concentrations of sodium and more especially of calcium ions delay both the phase of rapid exchange and the phase of declining permeability. The rate of formation of perivitelline fluid is greatest during the period of high permeability.