CHLORIDE AND TOTAL OSMOTIC PRESSURE IN THE BLOOD OF MARINE TELEOSTS

¹ From the Mt. Desert Island Biological Laboratory, Salisbury Cove, Maine; the Stazione Zoologica, Naples, Italy; and the Laboratory of the Marine Biological Association, Plymouth, England

An effort has been made in this study to obtain data upon the plasma chloride and total osmotic pressure (delta) of the blood of marine teleosts under their normal conditions of existence in the sea. For this purpose hook-and-line specimens, bled immediately after catching, have been used as the best available material. Studies upon pollack, cod, sculpin, flounder, mackerel, and conger indicate an appreciable physiological range of variation in both chloride and delta, with no detectable correlation between the two in any given species.

The average plasma chloride for many species studied has been found to vary from 150.6 millimols (pollack) to 172.6 millimols (conger) per liter. Supplementary chloride data upon specimens removed from the Naples aquarium and upon Orthagoriscus mola (from a large tunnynet) are reported.

It has further been demonstrated that both plasma chloride and delta are as a rule considerably elevated in fishes caught on a long line or by net, and in fishes bled only after a delay and rough handling. It is emphasized that this represents a serious source of error in studies upon normal osmotic pressure relationships and upon the relative tonicity of the body fluids in marine teleosts.

Certain of the Labridæ have been found to contain in their plasma a blue or green pigment.