To the Editor: On Feb 1, 1965, I sent you a letter taking issue with some of Dr. Mauer's comments concerning "Crenated Red Cells in Spinal Fluid" which appeared editorially in the Journal, 108: 451, 1964. It included copies of correspondence I had with Dr. Mauer as well as an alternative explanation for this phenomenon.
In essence Dr. Mauer's explanation depends on the idea that "Cerebrospinal fluid is 3.5% hypertonic with respect to blood plasma, and water loss from the red cell with crenation would be expected to occur promptly in this fluid."
The concept that CSF is hypertonic compared to blood plasma is correct on the basis of osmolarity, ie, osmolar concentration per unit volume of solution (plasma); but it is incorrect on the basis of osmolarity, which is applied to osmolar concentration per unit weight of solvent (water). It is a biologically significant point that all body cells