NONELECTROLYTES

Abstract

There are two theories as to the nature of the cerebrospinal fluid: one, that it is an active secretion; the other, that the fluid is a simple dialysate of the blood plasma formed by capillary pressure filtration. The evidence bearing on these two views has been reviewed by Fremont-Smith,¹ who came to the conclusion that there is no good evidence that the cerebrospinal fluid is a secretion and that the evidence as a whole is overwhelmingly in favor of dialysis. A good part of the evidence on which this conclusion is based comes from a study of the distribution of chlorides and other electrolytes between the plasma and the cerebrospinal fluid. If a simple membrane equilibrium does exist between the fluids, the distribution of ions between the two phases should follow the same physicochemical laws that have been shown to determine the distribution between the plasma and dialysates separated