Sodium regulation in the crayfish Astacus fluviatilis. I. The normal animal

It has long been established from osmotic pressure determinations that the fresh-water crayfish Astacus flttviatilis controls the concentration of solutes in the blood quite rigidly at a level (A = — o-8o to — o-8i ° C.) far above that of the outside medium (e.g. Scholles, 1933; Schwabe, 1933). The concentrations of inorgani