mouths er years. d) The platelet count, unlike the fluctuating tetal lewkecyte count, falls in s regular fashion aad reaches a low on the XUth day. Some recovery is cvident early; however, as with the ether elements, recovery may not be complete several months after exponure. 4. As an index of severity of exposure, perticularly in the sublethal range, the total white or newtrophile counts are of limited usefulness because of wide fluctuations and because several weeks may be required for maximum depression to become evident. The lymphoryte coant is of more value in this regard, particnlarly in the low dose range, since depression eccurs within hours of exposure. However, since a marked depremsion of lymphocyte counts erceurs with low doses and, since further in- crease in dose produces litth 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 as a convenient and relatively easy direct method of determining the degree of exposure. References 1 Rrevher, G.. and Cronkite. F. Po: Murphology and Enumeration of Human Platelets, J. of Applied Pa parndogy. 3. WS, 1808). 2 Waleak, J. en Ame wee Applications of Bone Significance Levetion, Annsls of Neth. stat. %: 48-108, 054. 4. Rearabeum, 6. : Tables for a Nonparacectric Test of Dieperuien, Anacis of Noth. Sat... %: B-O, TemR, & Men, W. J.: The Statistical Mgn Test, J. Amer. Stet. tesee., 41: SGT-A08, Des. @ Queeeutite, M. W.: Acseriated Mensuremect, Chap ter 3, Ordering Teet, Academéec Prem ier.. Pubiiahera, New York, 1902. 7. White, C.: The une of ranks in 0 test of signi ceare fer comparing two trestascets, Biowrtrics A:33 1982 & Moura, 1. K.: Nonparametric stetisticrs fer poycho ingics! reavarch, Peprh. Boil. 50: 122. TORR. ®& Wintrove, M. M.: Clinical Hemetetegy, Lee and Febviger, Phil. 1967. 16. Standard values in bleed, Air Force Techairal Be port No. 6588, 1961. Pwhitehed by Naticani Acad emy of Brirere. 11. Minot, G. BR. and Spertiag. RB. G.: The eect os the blood of irradiation, espertaliy short-weve length Roentgen ray therapy, im. J. Med. Sci. i168: 215, 1924. 12. Ouxhterere, A.W. ond Warren. 5.: Medics! e@erts of the atomic bomb in Japan. McGraw-Hill Beok, lec., Mew York. 1806. 13% LeRoy. G. V.: lematulegy of atomic bomb casealthes, ireh. int, Ved, sé: GBI, 18. 14 Jacobeoe, I. (0), Marks, FE. R.. sad Lorens, N.: Hematotogical Fifects of ionising radiations, Rediology 52: 371, 1948. Li. Cronkite, E. P.. and Brecher. A.: The protective effect of granulocytes in radiation injury, ins. NOY. bead. Net. 39: 815, 10. 14 Mnetl, Fo M.. and Newt. J. V.: Hematniogic studies in Hiroshima aad a coatrol city two years after the atomit bombing, .irck. iat. Med. ag: 3B, 1948. 17. \iinaeeive. Yo: Hematotegte stedies of trradtated survivors ia Hiroshima, Japan, Arch. [et, Wed. $f: 310, Hh. 1%, Hewpelwana, 1. H., Linco. HL, and Hoffman, J. Q.: The acute radiation syodrome: A atudy of nine canes and a review uf the problem, iva. Int. Med. Je: J7R, 1 19. Hastetriik, R. J.: Cates! repoect of fuer individuats accidentally e<poeed to gamma radiation and seutrons, Argonne Nativeal Laboratory, Jaa. 100% WB. Croakite, EP. and Brecher, G.: Defects in bewo- Tests for the Median Which Are Valid Under Very stasis preinceed by wholiebudy irradiation, Jusiab (emeral Conditions, J. Macy, Jr. Foundation, Trassactions of the afth cusfereece ca blond coagulation, New Vorn, 1962. vo, Tieete - EL: 3. Reweoboum, £8. : Tabée fer « Nenpasumstric Test of diser Nfat. lseor.,, 44: 342- a eee or mere. The initial rise in tetel white count is dus te a newtrephilic leubecytosn. e) The drep m lymphocytes is carly and profound. Litie or ne evidence of recovery may be apparent several months after exposure, and wecre te nermal icveis may not occur fer

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