- 16 island were made in approximately the same area, a coral-filled channel open to the sea at high tide, lying near the north end of the island. The data are summarized in Table 3 and Figures 3 and 4. The radioactivity in Kabelle Island fish muscle tissue showed levels of about 2.7 wc/kg on March 26, 1954. By October 1955 levels had dropped to less than .030 uwc/kg, which is less than (1/2)8 that of the March 1954 samples and the liver samples (1/2)? for the same period. Decline and decay of radioactivity show differences in rate, the former declining at a slower rate than decay the first 100 days after March 1, 1954, and then at a greater rate thereafter; thus the curves appear to be approximating each other at the present time. Differences in rate of decline and decay might be explained by the postulate that in the first 100 days after March 1, 1954, the radioactive materials existed in greater abundance than could be utilized by the fish so that during this period the fish tissues were more or less "saturated" with the materials. As the radioactivity decayed and was dispersed with time, the tissues declined in radioactivity at an increasing rate commensurate with the amounts available in the food chain and in the surrounding water. Decline in amounts of radioactivity in omnivorous and carnivorous fish indicates some differences in rate, at least for the first 100 days (Fig. 4). These differences decreased with passage of time. The grouper and damselfish in Table 3 represent rather common species of carnivorous and omnivorous fish, respectively, and are the best repre- sented, of all the species, in the collections. For the most part the averages