- 18 compare with those of omnivores and carnivores generally. In the data there appears to be a distinct pattern of relative amounts of radioactivity in different organs which is maintained more or less constantly, indicating that the activity in the various tissues declines at approximately the samerate. Most of the decline curves and, at least the decay curve for muscle, deviate from a straight line, and although the curves indicate some mixture of isotopes, they do not apparently contain similar ratios of isctopes to those found in the mixed product curve of Coryell and Sugarman (1951)8, The distribution of radioactivity in the fish from various parts of Rongelap and Ailinginae Atolls is summarized in Table 4. By October 1955 radioactivity averages of fish muscle tissue ranged from 0.009 uc/kg at Rongelap Island to 0.033 wc/kg at Labaredj Island. Liver tissues ranged from 0. 20 uc/kg in Ailinginae lagoon to 1.6 ywc/kg at Kabelle Island (Table 3), Extreme rangejf the samples were, for muscle, 0.003 to G. 10 we/kg and for liver, 0.026 to 4.7 yc/kg. In general, the activity was highest in the northern islands of Rongelap Atoll. Enibuk Island (Ailinginae Atcll) and Rongelap Island (Rongelap Atoll) appeared to be similar in activity. The coefficient of variation for muscle tissue radioactivity in Kabelle Island fish, where 12 or more specimens were involved, varied from 46 to 143 percent. In liver tissue the coefficient of variation ranged from 64 to 119 percent. There appeared to be no decrease in variation with time.