~j~ lower foliage of the plants. ‘ Represen:acive valuas for K and Ca-137 in three of the common species are given lower part of Table I. Potassium contents of the in ihe upper foliage have consistently proved to be much higher than those in the lower foliage. On the other hanc, Ca and Mg levels have been consistently higher in the lower than in the upper leaves. In the case of Cs-137, the samples of a the pattern is consistent in particular species, but ences between the species. there are differ- In Messersychmidia and pandanus, Cs-137 levels area higher in the upper than in the lower foliage, whieh is the game pattern that was obsercved in the aquash grown in the greenhouses. a he of in contrast, 3caevola shows higher levels Cs-157 in the basal chan in the upper Leaves. In one instance the effect of mineral fertilization in the field was tested. Two 1/80 acre plots in a coconut grove on Ronagelap Island wera treated with a broadcast application of KCl in August 1958, at a rate of 140 pounds K30 per acre. dominant ground vegetation, a grass The (Lepturussp.) was sampled in March 1959 from the fertilized and control areas. Average values for the content of K(meq per 100 dry gm) and Ca-137 (a/m/gm) were as follows: Controle 10.1 K, 65 C3~-137; Fertilized-16.5 K, 20 Cs-137. Samples from the same locations