ON CERTAIN PHYSIOLOGICAL DIFFERENCES BETWEEN DIFFERENT PREPARATIONS OF SO-CALLED "CHEMICALLY PURE" SODIUM CHLORIDE

¹ From the Marine Biological Laboratory, Woods Hole, Massachusetts, and the Department of Physiology of the University of Pennsylvania

1. Of five commercial brands of C. P. sodium chloride that have been studied, one is apparently always harmless and two always destructive to the erythrocytes of certain teleost fishes; one and perhaps both of the others are intermediate and somewhat more variable in their properties.

2. There is indirect evidence that the destructive effect of the toxic brands is due to the presence of an impurity of some sort, which has, however, not been identified. It is not removed by a single recrystallization of the salt.

3. Similar though much less striking differences have been found in the physiological action of the brands of sodium chloride in question upon newly-hatched Fundulus and less certainly upon the eggs of Arbacia. No constant differences have been noted in the case of mammalian erythrocytes or in that of the cilia of Mytilus.

4. It is suggested that in all physiological work in which sodium chloride is used particular attention should be given to the possibility of errors resulting from the presence in the salt of unknown toxic impurities.