In order to prevent the growth of water-mold when the eggs of Osmerus dentex are being hatched, it gives very satisfactory results to use the sea-water containing salinity of 8.816%. (w. t. 13.08°C)-10.13% (w. t. 15.68°C). By, means of laying a hatching-box in the mouth of a river, the growth of water-mold on the eggs can be prevented with ease, and consequently the rate of their hatching can be raised. On the other hand I have made an experiment of the resisting power of water-mold to sea-water.
