~103- AECD~3446 fe the amount of water pumped could be closely estimated. The amount of - passing from the pump to the net was measured with a Sparling meter, but constant flow was established, the water was usually shunted around the 2tO protect the meter from unnecessary damage. The water flow through hung on the showeroutlet was 2 to 3 gallons per minute. Since the nets were re-used, contamination of one sample by another deupon removing the entire sample after each catch, ‘this required special attention. With the fine-meshed All nets were thoroughly washed down and ‘that had become clogged were vigorously rubbed together by hand in water. yme occasions, the meshes were microscopically examined to determineif were clogged. The wash water was saved, allowed to settle, and the residue decantation, added to the sample. All samples were preserved in formalin, Plankton activity in disintegrations per minute per gram of wet drained ople, by area, by sampling method, and by mesh size is givenin Table 2. Two eral conclusions may be made from the data presented in the Table; (1) Catches the fine-meshed nets, 125 or more meshes per inch yielded the highest counts, ches of macroplankton from the night collections were low in activity. There- , in’ comparing catches between areas, or depths, or time of day, it would that only counts from the fine-meshed nets should be used. (2) Activity eatest near the Eniwetok Shot Islands and next greatest in the Bikini Target If the definition of the term "background" is extended to mean the count [similar type of sample at a control station, in this case from Likiep Lagoon, om out eight times background; andoff Eniwetok Island,background. — At a depth of 15 feet, catches made in the fine-meshed nets in the same ww ° 1g the activity in the plankton immediately off Bikini Island was "background"; Bikini Target Area, about three times background; off Eniwetok Shot Islands, ea during daylight hours gave higher average counts than those collected during urs of darkness. Values in d/m/g for Bikini Island during the day were 70, 164, , 38, 12, and 3; at night, 6 and 3; and for Bikini Target Area, day, 86; night 0. tly, her catches were not comparable by the criteria established above. To find out if the activity of the plankton varies with depth of sample, 18 vity of catches comparable as to mesh size, time of day, and area were com- d, For Bikini Target Area the radioactivity expressed as d/m/g of three uw UNIVERSITY ARCHIVES UNIV. OF W's th PEORAR Vk