The osmotic changes in some marine animals

Abstract

Since Bottazzi's (1897) first determinations of the osmotic pressure of the body fluids of various marine animals many researches have been performed by other authors, particularly in reference to the permeability of the membranes separating the body from its surroundings. Bottazzi (1897, 1906, 1908, b) investigated individuals belonging to very different groups of animals, and found that the osmotic pressure of the body fluids of marine invertebrates, and of elasmobranchs, is very similar to that of the surroundings, while the osmotic pressure of the blood of teleosts is quite different. Changing the osmotic pressure of the medium, the osmotic pressure of most marine invertebrates, and of elasmobranchs, was shown to change in the same direction (L. Fredericq, 1882, 1904; Quinton, 1897; Dakin, 1908) and to reach, finally, the value of the former. The blood of teleosts is much more independent of the medium, for it shown to change only about 30 percent, in concentration, on transferring the animals from sea water to fresh water or vice versa (Dakin, 1908; Dekhuyzen, 1904: Sumner, 1905); other authors, however (fredericq, 1904: Garrey, 1905) could not field even these variations.