EFFECTS OF IONIZING RADIATION or more. The initial rise in total white count is due to a neutrophilic leukocytosis. c) The drop in lymphocytesis early and profound. Little or no evidence of recovery may be apparent several months after exposure, and return to normal levels may not occur for months or years. d) The platelet count, unlike the fluctuating total leukocyte count, falls in a regular fashion and reaches a low on the 30th day. Somerecovery is evident early; however, as with the other elements, recovery may not be complete several months after exposure. 4. As an index of severity of exposure, particularly in the sublethal] range, the total white or neutrophile counts are of limited usefulness because of wide fluctuations and because severnl weeks may be required for maximum depression to become evident. The lymphocyte count is of more value in this regard, particularly in the low dose range, since depression occurs within hours of exposure. However, since a marked depression of lymphocyte counts occurs with low doses and, since further increase in dose produces little more depression, this index is of little value at the higher doses. 5. Platelet counts showed a regular pattern of change in the present studies, with the same time of maximum depression in all exposure groups and with the degree of depression roughly proportional to the calculated doses. It appears, therefore, that the platelet count has considerable promise in the sublethal range ag a convenient and relatively easy <irect method of determining the degree of exposure. 3. Rosenbaum. S.: Table for a Nonparametric Test of Location, .nnals of Math. Stat.. 2: 146-150. 1954. . Rosenbaum, S.: Tables for a Nonparametric Test of Dispersion, Annals of Math. Stat., 24: 663-069, 1953. . Dixon, W. J.: The Statistical Sign Test, /. Amer. Ntati ..asoe., 41: 557-566, 1946, ot 62 . Quenouille, M. H.: Associated Measurement, Chapter 3, Ordering Test, Academic Press Inc., Publishers, New York, 1052. . White, C.: The use of ranks in a test of significance for comparing two treatments, Biomctrics 8:33, 1952, . Moses, L. E.: Nonparametric statistics for psychological research, Psych. Bull, 49: 122. 1952. . Wintrobe, M. M.: Clinical Hematology, Lea and Febiger, Phil., 1951. 10. Standard values in blood, Air Force Technical Report No. 6089, 1951. Published by National Academy of Science. 11. Minot, G. R., and Spurling, R. G.: The effect on the blood of irradiation, especially short-wave length Roentgen ray therapy, .im. J. Med. Set. 168: 215, 1024. 12, OQughterson, A. W., and Warren, S.: Medical effects of the atomic bomb in Japan. McGraw-Hill Book, Ine., New York, 1956. . LeRoy, G. V.: Hematology of atomic bomb casualties, dreh. Int. Wed. 86: 61, 1950. Jacobson, L. ©., Marks, E. Ro and Lorenz, N.: Hematological Effects of ionizing radiations, Radiology 32: 371, 1940, 3. Cronkite, FE. P., und Brecher, \.: The protective effect of grannlocytes in radiation injury, inn. N.Y. Aend. Sei. 302 815-883, 1955. . Snell, F. M., and Neet. J. Vo: Hematologic studies in Hiroshima and a control city two yeurs after the utomic bombing, ..reh. fat. Wed. 84: 569, 149, 1%. Yamasoiva, Y.: Hematologic studies of frradiated survivors in Htroshiout, Japan, ref. dnt. Med. of: 310, 1953, 1s. Hempeimann, 1. H., Liseo, H., and Hoffman, J. G.: The acute radiation syndrome: A study of nine 1. Brecher, G., and Cronkite, BK. P.: Morphology and Enumeration of Human Vlatelets, /. of .tpptied Physiology, 3: 365, 1950. 2. Walsh, J. E.: Applications of Some Significance Tests for the Median Which Are Valid Under Very Generali Conditions, /. air, Stat. .ssoe., 44: 342~ 355, 104). causes and a review of the problem, an. fut. Med, 862 279, A952, . Hastertik, R. Jo: Clinient report of four individuals aceidentally exposed to gamma radiation nnd nen- trons, Argonne National Laboratory, Jan. 153. 20. Cronkite, K.P. und Brecher, G.: Defects in hemestasis produced by wholebody irradiation, Josiuh Macy, Jr. Foundation, Transactions of the sfth conference on blood coagulation, New York, 152. >. References