peak was calculated. This value was subtracted from the com- posite .134 MEV and .145 MEV peaks in the samples. The remainder was considered to be from cel41, The values obtained for all isotopes were corrected to the date of collection of the sample. DISCUSSION OF RESULTS Ocean survey samples During the Collett survey (August 8 to 14) gamma spectra were made on plankton samples.and smaller peaks at 0.0% MEV, Pronounced peaks at 0.055 MEV later identified as those from tungsten-185, were observed in some samples but not in others (Fig. 2). When the station positions for those samples con- tributing the two peaks were plotted on a chart of the area sampled, a pattern of occurrence was observed (Fig. 3). The plankton specimens containing the wi85 were taken in three areas. The region containing the highest levels of wi85 in the plankton (19,000,000 d/m/g dry weight) centered 155 nautical miles northwest of Eniwetok Atoll, coincided with an area of high total radioactivity, and was about 180 miles in diameter, with @ tongue of activity extending to Eniwetok Atoll. The northern and western boundaries of the radioactive area were not determined. A second area, containing lower levels of wi85, was approximately 90 nautical miles west and south of Eniwetok and “es, gc ™ poe