less with distance from shot islands, with the exception of Rigili, and were least to the south and southeast within the atoll. The average increase in all tissues from pre-shot to post shot activity was greatest by far at Bogallua (Fig. 6 and Table 10). Although Engebi and Bogallua were about equidistant from the target center, the amount of radtoactivity in fish tissues at Bogallua showed an increase of from 4 to 18 times that of the fish tissues at Engebi. The data indicate that, of the radio- active materials taken into the gut at Engebi or Bogallua, a greater proportion reached the four other tissues bone, 4.6 liver ( muscle, skin, ) of fish at Bogallua than at Engebi. Land Plants The plants collected before and after the shot included 15 species of flowering plants, 4 species of fungi, and 1 species of lichen. Some of the plants were collected at only a few of the stations. A check list is given in the Appendix. In gen- eral, collections were made in the areas where rat traps were set (p.62), but a few were made along the beach or wherever it was possible to obtain certain of the species. Some plants were pressed directly in the field for future use in autoradiography; others were preserved for identification. Radiological assay of the plants followed the same procedure used for the other organisms. stems, roots, Counts were made on leaves, and fungi. - 59 - flowers, fruits,