Change of Weight of Marine Animals in Diluted Media

Abstract

1. Several species of marine invertebrates, and an elasmobranch, have been kept in diluted media. The increase of body weight so caused was compared with the resulting dilution of the body fluids. 2. The bounding membrane of the invertebrates was permeable to salts when the animals were immersed in diluted sea water. 3. The bounding membrane of the elasmobranch was semipermeable, i.e. permeable to water but not to solute. There is a close quantitative agreement between the osmotic swelling observed and the diminution of the osmotic pressure of the blood.