12 fishes is not known and the chemical form in which the radio- nuclides are present in the lagoon waters can only be surmised. We do not even know, for example, whether the radionuclides and their stable isotopes are present in the same chemical form. Furthermore, there are no uncontestable data on the trace element content of lagoon waters and probably will not be until the techniques of sampling and processing seawater samples is greatly improved. However, some hypotheses can be made and conclusions can be drawn from certain data. All of the fallout radionuclides at Bikini are found in the surface of undisturbed soils. in 1969 were 35 ne, 6000, 6500, The predominant radionuclides 90, 125 Sp, 13745, In the crater sediments only four predominate: and 20755. Be, £900, 905, and 20755, although many more are present in smaller quantities. The soils and sediments are now the principal reservoirs of radio- nuclides at Bikini. ‘The radionuclides are available to the land animals through the vegetation, or other animals, where there is selectionof specific radionuclides, or through direct ingestion of soil. In the latter case, the animal selects certain | radionuclides from a wider variety of nuclides than is in the vegetation. | Similarly, the marine animals may ingest radionuclides by eating another organism or by ingesting sediments. In addition, the marine organism may absorb radionuclides directly from the