O RADIUM (pCi/gm) 12 0.05 oO 0.20 0.10 | | 0.30 CALCIUM (gm/gm) Fig. 7.—The variation in the concentration of radium with the degree of calcification for the Rhedophyceae is no correlation between radium or thorium and calcium; the calculated values of the correlation coefficient were not significantly greater than zero; (2) the correlation between uranium and calcium is highly significant (P < 0.001). The result for radium is very surprising. Since there was no direct relationship between radium or thorium and the calcareous matertal, regression coefficients for all algae were then calculated for their correlation with the concentration of protein nitrogen. The results are found in Table 3 and show that there is no direct relationship with protein nitrogen for radium or thorium. There is, however, a highly significant inverse correlation with protein nitrogen for uranium (P < 0.001), but this, of course, follows from the strong inverse correlation between calcium and protein nitrogen. From a careful examination of the data shown in Figure 4 for the relationship between the concentrations of radium and calcium in these algae, it appeared that regression analysis according to phyta might lead to meaningful correlations being found. Regression analysis of all of the data for each of th: three phyta did not lead to calculated values of th. correlation coefficient which were significantly greate than zero (P > 0.1). However, if all of the result: which are not included within the limits X¥ + 3 (where XY and o refer to any analytical parameter fo each separate species) are rejected, then highly sig nificant correlation coefficients (P < 0.001) are foun for the Rhodophyceae and Phaeophyceae, but the cor. relation coefficient for the Chlorophyceae is still no significant. The experimental values of concentrations of ra dium and calcium for the Rhodophyceae and Phaeo- phyceae are shown in Figures 7, and 8, respectively The data points which are hatched are those whicl were rejected in the second regression analysis. Thi- analysis clearly demonstrates differences according tc phyta for the concentration of radium with increasin: calcification. The concentration of radium, on the ont hand, increases with increasing degree of calcification in the Rhodophyceae (R = 0.51), is completely variable in the Chlorophyceae, and on the other hand de-