meshed nets listed in Table 1. The higher value of the pair twas from 2 coarse mesh net 5 times and from a fine mesh net 5 times on the ash weitaL vacis and tne same was true on the wet weight basis. In only half of the cases was tie same mes size hisher on both the ash and the wet basis. All of this inuicates randomness, or ia other words, a lick of correlation between mesh size and specific activity. In our earlier reports, heta radioactivity of plankton as deter:.inec in me thaneff Low counters has been reported on the wet basis so that tne specific activity of plankton may be compared with that of other substances. Tnis involves attempting to drain water uni- fornl; from the plankton samples at the time of preparing the plates. Te varving water content of the planktonic organisms causes uncer- talnty in evaluating the amount of wet plankton being radio-assayed. It nus snown (UWFL-53:19) that if results were based on the amount of planktonic ash ratner than on the amount of wet plankton, the variat Llity in radioactivity of replicated tows was reduced to only ore nalf the v.lue obtained on the wet basis. Similuriv, tne present data for Rongelap Atoll were more con- siste it on an ash than on e@ wet basis. The greatest disparities be- tween the two values for palred tows occurred in the 1956 collections, as seen in Table 1. At Kabelle, the ratio between the two values was only 3.6 on the 2sh basis, but 8.9 on the wet basis, and at RongelapnI. only 4.2%, .21 busi, but 8.6, wet basis, so that here, as at Eniwetok, Ate”, tne variibility is only half as greit on the ash as on the wet basis.