-17- The per cent of activity remaining on the filters in those samples filtered at date of collection (August 8 - 14, 1958) 1s 5 to 170 times that found in the samples filtered January 13, 1959. Thus a considerable amount of leaching occurred during the intervening period. of plankton from the Collett survey, other specimens collected at Eniwetok, Bikini, Rongelap, Ujelang, Utirik and Wotho Atolls in the Marshall Islands, Caroline Islands, Kapingamarangi Atoll in the Tarawa Atoll in the Gilbert Islands, and Kusaile and Ponape Atolls in the Senyavin Islands were examined by gamma spectrometry for the photopeak (0.055 MEV) of w185, The isotope was found only in samples from Eniwetok, Bikini, Rongelap and Ujelang Atolls. Eniwetok Atoll Samples Chemical separations were made on Seaevola leaves from Belle Island by ton-exchange and precipitation methods. In the anions from the ion-exchange column only the peaks of energy represented by wi85 and Zr99-Nb?? were observed in the gamma spectra. Rul03+106_p,103+106 were driven off by heat in the ashing process. In the precipitation separation, specific for tungsten, which is only the 0.055 MEV photopeak and the 0.03