BRD etl d\n Rech adh a on Hae Ba a! Raecicati De Waal| ideeee aie ships rium sion and the s of acthe and 1. e to phyta does not alter the significance of the correla- and that their concentration in the organism would be directly proportional to its caleium content. Although tion. As might be expected, the correlation between protein nitrogen and total organic material was also there is no biological evidence of this in a calcium carbonate system, there are many instances of radium localization at sites where calcification occurs in the highly significant (@ = 0.57 for f = 64). However,if bones of animals. Inferences have been made concerning calcium metabolism on the basis of this localiza- the regression analysis is carried out according to et MMR orem ranic ined. <remgl enon ne eat 11 phyta, the correlation for Chlorophyta and Phaeo- phyta is highly significant while there is no correla- tion.*) There is, thus, the widely held belief that In all of the species of algae analyzed in this study the apatite (calcium phosphate) system. Similarly, tion for the Rhodophyta. radium may be used as a tracer for calcium at least in calctum carbonate is laid down and normally retained as the orthorhombic crystalline form aragonite, which, while being metastable under manyconditions, is the most common modification in warm tropical waters.) The exchange or coprecipitation of radium or uranyl ions with calcium in the aragonite lattice is possible because there should be neither steric problems nor restrictions on the formation of solid solutions due to ionic size (particularly at the extremely orode:ontion vith ‘Ing while data for uranium metabolism are relatively scarce, the uranyl ion is found in all natural apatite deposits. In the case of thorium and its solution chemistry under the conditions salinity found in seawater is complex, it whether any thorium would be present form to act as a tracer for calcium. The relationships between radium, thorium, and uranium with calcium are shown in Figures 4 to 6. The lines drawn through the experimental data were derived from the regression analyses for each set of low concentrations of these two ions). Therefore it would be expected that either of these two ions ' to data. These analyses (Table 3) show that (1) there (Rat++ or UOT) could act as a tracer for calcium spit ABI. 1S ans eheneacpeniea T4 ° | URANIUM (jgm/gm) SS FOENONE Lee ening 2.0 0.5>o 00 Oo joo 0 Oo O CHLOROPHYCEAE A On ! 0.1 D RHODOPHYCEAE oO ions, whose of pH and is uncertain in an ionic A PHAEOPHYCEAE | 0.2 | 0.3 0.4 CALCIUM( gm/gm)} Fic, 6.—The variation in the concentration of uranium with the degree of calcification of the algae