nd Assuming, as these results indicate, that activities in coarse and fine meshes do not differ, the ratio of coarse to fine should be unity. The ratios in Table 9 were used to determine variability on the wet as opposed to the ash basis. On the ash basis, variance was only half as great as on the wet basis, thus, ash is considered the better basis. Con- version to logarithms was necessary to normalize the skewed (with peak toward the left) frequency distribution of the two arrays of ratios. Figure 12 shows 90, 0001" the decline for MIKE CRATER plankton samples at 6 localities on a wet weight basis using the data of Table 7, with the two values for paired tows averaged. Except at the Mike crater and Vera the declines were steep, ranging from average for all locali- ties combined of -1.96, wet basis, and -1.74 on the ash basis. The WIDE PASSAGE d/m/g x 103 wet -1.8 to -2.61 as seen from Table 1, with an 10,000 1000,- gradual decline (-1.0) at the Mike crater could be the result of continu- ous leaching of radioiso- topes, from the crater into the water, thereby maintaining the activity of the plankton. At Vera the trend is too F O.IF 100 1. 1000 10 —L. too DAYS AFTER MAY /4,1954 poorly defined (P > 10%) to permit comparisons. Fig. 12 1000 10 1 100 * i000