values thereafter inthe course of the study. ‘The hiptiotyte couqts fel ta below control fevedis im the first few days, and remained at a level approximately 75 per cent of the control value throughout most of the remainder of the observation period, In the Ronpelap and Aibapinae groups the fluctuations inthe total leukocyte count were ae counted for abhmost Patrredy by changes ip the total neutrophile count. ‘The Ronperik preoup di fered since the changes intotal levkocyte count were retlected almost equally in the lympho evte and neutrophile count. The significance of this difference tn response i the two groups is : o hot apparent. The platelet counts (Fig. 4.6) were not markedly depressed when the tuittal counts were * taken during the third week. At the end of the third week, however, the platelet count began to fall to reach a low of approximately 60 per cent of control levels at the end of the fourth week. following which a second depression was noted. The platelet counts were at a level of 80 per cent of the control value at the time of the last observation during the eighth post-exposure week, 4.9 . ere se The value then returned to approximately the control level at the start of the seventh week, MONOCYTES AND EOSINOPHILES, ALL GROUPS From Table 4.2 it is seen that the mean monocyte count for the Rongelap group rose abruplly from an early value below control levels to a well defined peak on day 12, following which it fluctuated at values below the control level for the duration of the observation period. A similar time trend was noted in the Ailinginae and Utirik groups. The eosinophile count in the older age individuals, Rongelap group, rose from very low levels observed on day 3 to values approximating 35 per cent of control during the second week, where it remained from the third to the fifth week (Fig. 4.7). The counts then decreased (P< 0,01), and remained at a value approximately 15 per cert o° control throughout the remainder of the study. The time trend of response was similar in the younger age individuals, however, changes in the younger age group wererelatively greater {f considered in terms of the control values, Similar trends in eosinophile count were not evident in other exposure eroups, -— ~ It is possible that the rise in eosinophiles represents that reported as occurring to three weeks after short-wave-length irradiation”.“ 4.10 Ty -. two HEMATOCRIT, ALL GROUPS The hematocrit values for all exposed groups are shown in Table 4.8 and in Fig. 4.8 (a detailed breakdown of hematocrit by age and sex for control groups is given in Table 4.1). When hematocrits were first done on the 22nd day, mean values for the Rungelap and Ailinginae groups were below those of the control population, A significant trend in values after this time could not be detected statistically. 4.11 t : : MORPHOLOGY OF PERIPHERAL BLOOD Significant morphologicai cellular changes, normal mononuclear cells* seen in a number of were not observed, Similarly altered cells have ‘evaluation of these changes in the present study of the hematology slides. with the exception of a small number of abindividuals during the period of neutropenia, been observed previously.” Complete would necessitate an exhaustive serial study *There was considerable difference in opinion in respect to classification of these cells. They were classified as atypical monocytes, degenerating lymphocytes, atypical myelocytes, monocytoid lymphocytes, and lymphocytes in transition to myelocvtes. At the time of this re~- 81 SN nett © port there was no unanimity of opinion in respect to classification and significance of these cells.