Part of the activity in some of the tissues may be due to naturally occurring K**, However, the amount of potassium per unit wet weight in the skin and muscle is approximately the same and in either instance would amount to 5 d/m/g or less. If K*° were mainly responsible for the increase in activity in the tissues, then one would expect skin and muscle to be approxtimately equal in activity. Muscle, however, is more radioactive. Table 4.17 — RADIOACTIVITY OF BIRDS, POSTSHOT* Proventriculus Type of bird n Igurin Tern Eniwetok Tern Japtan Tern Rigili Tern Runit Tern & 1 4 4 3 Aaraanbiru Aaraanbiru Rojoa 2 Island Engebi Tern Shore 1 bird Shore 2 bird Ternt 1 Gizzard Muscle Bone and and Gut and Liver contents contents n contents n Lung 1.2 0.85 0.37 14 0.75 0.26 0.16 0.22 0.72 30.54 1.0 0.55 0.37 823 0.74 0.083 0.12 0.13 3.6 1.1 Lt 0.36 0.86 0.78 14 2.0 6.6 8.5 19 0.63 7.6 2.5 Skin 0.15 0.40 0.14 2.1 0.83 0.23 0.21 0.20 4.7 10 «3 #1 4 4 3 0.41 0.12 0.18 13 3.7 0.89 1.5 3 3.9 28 3.2 96 1 94 2 1 19 220 2 0.86 17,000 * Measured in disintegrations per minute per gram (x 1000), wet sample. t Bird had been blown to pieces by the shock wave. Radioactivity is that of surface contamination. The fact that the activity within the bone was zero in both the birds and rats is of interest. In the 1949 radiobiological resurvey of Eniwetok, the amountof activity in the bone samples of rata was positively correlated with the radioactivity of the habitat, as indicated by surveymeter readings. The habitat of the rat specimens at the time of the present preshot collectiona had a low reading, in all cases being less than 1 mr/hr. 4.7.4 Analysis of Organs and Tissues, Postshot In Table 4.16, the data for the postshot rat collections are given. In a comparison of the same organs and tissues in six specimens (except for the digestive tract), the disintegration rate does not differ in any instance by more than a factor of 7. In a comparison of the same organor tissue in the different specimens of birds collected at any one station (Appendix F), greater variations in disintegration rates are found than were evident in the rats. The maximum variation occurred in the livers of the Rigili terns, where the greatest difference was by a factor of 470. 4.7.5 Analysis by Island In general, the variability of activity for specific organs between individual birds pre- cludes the possibility of significant differences existing between average values for various collecting stations. However, when the average values for the different organs for individual 55 “"TNCLASSIFED