-10- entire picture, while only comparatively minute segments can be duplicated under controlled laboratory conditions. Only on the basis of the field studies can the relative merit of various sections of the problem be evaluated. Experiments now in progress at the Labo- ratory concerning the uptake of specific isotopes by aquatic organisms are based on survey data from previous Bikini and Eniwetok studies. Food chain transfers of material in the atolls are constantly in progress. These transfers follow the natural paths, while in laboratories the limitations of both space and variety of forms available restrict the scope of the studies. With the laboratory type of experiment, it is not possible to obtain the necessary data for determining if and at what time and at what level an equilibrium for the different long-lived fission products and unfissioned bomb material will occur within the various forms. The inability to predict the time of and level at which equilibrium will be reached within the