- 48 date regardless of area collected and by plotting the logarithm of these values against the logarithm of the collecting date, expressed as the number of days after March 1, 1954. The slope of the least squares regres- sion line computed from these data is -1.80, i.e., r = t7!: 80 Counting of the Rongelap lagoon plankton samples, the decay rates of which were reported in UWFL-42, was continued and the decay rates were found to be practically the same as determined earlier. For the March 1954 Labaredj sample, the July 1954 Kabelle sample, and the December 1954 Kabelle sample, the decay rates were -1.27, -1.38 and -1.35 reapectively. Water Both lagoon and island water samples were taken and processed in the same manner as previously but in addition new refinements to the technique were also tried. Results of the water analyses are presented in Table 13. (It is to be noted that the values in this table are in d/m andnot y/c.) With salt water samples that are prepared for counting by drying only, the amount used is limited by the quantity of salt remaining on the counting plate. For the October 1955 samples, 10 cc per plate were used. The values for the dried samples are listed in the column headed "untreated" in Table 13. F or the samples in the column headed "treated", about 5 cc of