Hematologic studies have been made on 935 randomly selected "control" (nonirradiated) Japanese residing in Kure, Japan, as part of an investigation on the irradiated survivors of the Hiroshima atomic bomb. An analysis of the findings with respect to age and sex indicated that there were a number of divergences from the usual Caucasian expectancies. Associated with a slight anemia in those over puberty there is a progressive increase in the mean size and hemoglobin content of the erythrocyte with increasing age, more pronounced in the male. The hemoglobin concentration in the cells is apparently reduced. The leukocyte counts decrease with increasing age and all mean values are somewhat elevated. Plasma protein levels as determined by the copper sulfate specific gravity method are higher than Caucasian normals. Reticulocyte counts are not unusual.

It has been emphasized that this "control" series does not consist entirely of normal healthy individuals, but that a considerable amount of disease is represented especially in regard to parasitic infestation. Also there is an appreciable nutritional imbalance present in the population. These two factors are probably of greatest significance in the interpretation of the observed divergences from Caucasian expectancies, but in view of the complexity of influences and inadequate data relative to each individual studied interpretations must be guarded.

ACKNOWLEDGMENTS I am indebted to General C. F. Sams, Chief, Public Health and Welfare Sections, General Headquarters, Supreme Command for the Allied Powers and his staff for making this work possible. Gratitude is likewise expressed to Dr. T. Myaki and K. Ryhu, Directors, Kure Mutual Relief Hospital, Kure, Japan, for their complete cooperation. Indebtedness is acknowledged to Dr. J. S. Lawrence for many helpful suggestions. Dr. J. V. Neel and Dr. K. Ishibashi, as well as the entire laboratory staff, deserve full credit.