EFFECTS OF WHOLE BODY IRRADIATION ON MARROW 485 normalities in the erythropoietic forms was reached after 2 days; that in the myelopoietic cells 4 days after exposure. On the 4th day, there was a distinct dose-dependent difference in these abnormalities between the high dose group (236-365 rads) and the low dose group (22-68 rads). 2. Some cytologic abnormalities, as seen in increased regeneratory activity of the marrow, were found in marrow smears 3.5 years after the accident, al- though the peripheral blood counts and mitotic indices of the marrow were within normal range. Their significance is obscure. 3. A careful cytologic evaluation of serially aspirated marrow samples during the first hours and days after whole body exposure proves to be an additional important aid in the assessment of the exposed individual and may well prove to be useful in determining the degree of injury and thus the prognosis. SUMMARIO IN INTERLINGUA 1, Serial studios del medulla esseva effectuate durante le prime dies in octo homines accidentalmente exponite a un mixte irradiation neutronic gamma. Esseva notate le occurrentia de un ver unda de anormalitates cytologic. Istos esseva identic con le anormalitates incontrate in animales experimental inter 1 e 3 dies post le irradiation del corpore total, Illos esseva reguardate como “mitoticamente connectite” e includeva le occurrentia de pontes chromosomal e de fragmentos chromosomal in mitoses, In cellulas de interphase, le major anormalitates esseva fragmentos nucleari (“karyomeros”) in le cytuplasma de erythroblastos, de cellulas myelocytic, e de lymphocytos e le presentia de bie multinucleate cellulas e de cellulas gigante. Le culmine del anormalitates in le formas erythropoietic esseva attingite post 2 dies e in le cellulas myelopoietic post4 dies a partir del exposition. Le quarte die, un distincte differentia in iste anormalitates esseva notate secundo le dose inter le gruppo a alte dosage (236 a 365 rad) e le gruppo a basse dosage (22 a 68 rad). 2. Certe anormalitates cytologic, manifeste in un augmentate activitate regeneratori del medulla, esseva trovate in frottis medullari 3,5 annos post le accidente. Tamen, a ille tempore le numeration in le sanguine peripheric e le indices mitotic in le medulla essevaintra le limites del uorma. Lesignification de iste anormalitates remane obscur. 3. Un precise evalutation cytologic de serialmente aspirate specimens de medulla durante le prime horas e dies post le exposition del corpore total se revela como un importante adjuta additional in le examine de un exponite subjecto. Il pare ben probabile que unta! evalutation va provar se utile in determinar le grado del injuria e assi le prognose in le caso individual. REFERENCES 1. Le Roy, G. V.: Hematology of atomic bomb casualties. Arch. Int. Med. 86: 691-710, 1950. 2, Kikuchi, T., and Wakisaka, G.: Hematological investigation of the atomic bombsufferers in Hiroshima and Nagasaki City. Acta scholae med. Univ. Kyoto 30:1-33, 1952. 3. Hempelman, L. H., Lisco, H., and Hoffman, J. G.: The acute radiation syndrome: A study of nine cases and a review of the problem. Ann. Int. Med. 36:279-510, 1952. 4. Shipman, T. L., ed.: Acute radiation

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