CHAPTER 3 METHODS $.1 PRESERVATION OF SPECIMENS All biological material, with the exception of plankton and rats, that was to be used for radioactivity analyses was placed on ice in an insulated container as it was collected. After return to the USS Oakhill the collecticns were packaged in cellophane bags, labeled, and moved i to a deep-freeze box for freezing and storage. During the air flight from Eniwetok to Seattle, the specimens were transported in an insulated container with dry ice. The specimens arrived at the University of Washington laboratory in a frozen condition and were immediately stored in a deep-freeze unit, where they remained until time for processing. Algae and plants that were to be used for autoradiographs or as herbarium specimens were dried and pressed in the field. All plankton samples, as well as fish and algal specimens, that were to be used for identification were preserved in 4 per cent formalin. $3.2 ASHING The samples were ashed and plated in much the same manner as previously described.' Briefly, the procedure was as follows: (1) Fish, invertebrates, birds, rata, and land plants were dissected, and approximately 1-g samples of various tissues were placed upon weighed 144-in. stainless-steel plates. Wet-sample weights depended upon the amount of tissue available and the activity of the sample at the time of dissection as determined by survey meter. The mean sample weight of 145 randomly selected samples was 1.17 + 0.074 g.* (2) The wetsample plates were placed in a drying oven at 97 to 99°C for 12 to 24 hr. (3) They were then cooled in a desiccator, and the dry weights were determined. (4) The plates were next moved to the muffie furnace for about 12 hr, during which time the temperature was gradually raised to 300°C then more rapidly to a maximum of 550°C; clam she ‘2 and corals were held at 600°C for 30 min. (5) After cooling, the ash was slurried with ethyl alcohol, and a clean glass rod was used to distribute it evenly on the plate. Following drying, a weightless amount of formvar in a 0.65 per cent solution of ethylene dichioride was added to prevent ash from being blown off the plate. After drying under a heat lamp, the plate was ready for counting. 3.3 COUNTING The samples were counted in two Nucleometer internal-gas-flow (pure methane) counting chambers. *In this report the value following the mean 1s the standard error. 19