There is no doubt in my mind but that the red cell vol- umes you found in the Marshallese are significantly smaller than what we have regarded as "normal". It 18 my impression that plasma volumes may also be slightly smaller but I will need a little more time to confirm this. There is nothing more I can add at the moment except perhaps to note that the correlations between BY and TEW, and between RCV and TBW appear to be better than I have seen for data on other groups of subjects. Please phone or write if you have any questions about the data or their interpretation. Sincerely, Wilijdam E. Siri Enclosures, Co: Dr, L. Meyer WES tpb