-37- account also for the similarity in the activity of these tissues first 100 days, to decline of radio- that of the soil. After the the rate of decline of radioactivity in all these tissues was slower than that expected by physical decay of mixed fission products, indicating that longer~lived radioisotopes had been taken up by these plants. The rate of decline of some tissues, however, was different from that of the soil, suggesting that some of the radioisotopes had been taken up by the plants and distributed selectively in the plant tissues. The rapid rate of of radioactivity in the adventitious leaves, fruits decline flowers, and of Scaevola and Messerschmidia indicates the presence of short-lived radioisotopes in these tissues. However, the rapid rate of decline of radioactivity in the scorched leaves, which were incapable of normal metabolic activity, attributed to a selection process. This apparent cannot be anomaly might be explained on the basis of the differential adsorption of fallout particles to the tissues, isotopes, surfaces of living versus dead on the differences in the foliar absorption of radioand on the different rates of removal of radioiso- topes by rain water. The results of the radiochemical analyses of the samples collected during the period of February 1955 to October 1955