PRADIO-ECOLOGY
1367
foliage consistently has higher K but lower Cs in the upper than in the lower
leaves. This would be in ‘accord with a previous study (Rediske and Selders,
1953) which showed Cs to function as a relatively immobile element in bean
plants. Data from additional field samples of a greater numberof plant species
are being accumulated at present with the hope ‘of establishing more clearly the
differences between species in this respect and the significance of the sharp
differences between the older and younger leaves.
The K and Cs-137 contents of field-collected Ieachates from Rongelap soil
have been shown to be greatest immediately following a dry period (Cole et al.
1960). Since there are marked seasonal differences in precipitation at Rongelap
_ Atoll this may have a bearing on some of the results which have been discussed.
REFERENCES
l. Core, D. W., Gessex, S. P., and Hetp, E. E. 1960. Tension Ivsimeter studies in glacial
till and coral atoll soils. Proc. Soil Sci. Soc. Amer. (in press}.
2. Jenny, H.. Veasus, J., and Marry, W. E. 1950. Hilgardia 20: 1-8.
3. Nusimta, H., Romney, E. M., ALexanper, G. V., and Larson, kK. H. 1960. Soil Science
89: 167-76.
4. Repisxe, J. Hl. and Secpens, A. A. 1953. The uptake and translocation of cesium byplants
U.S. Atomic Energy Commission, Tech. Information Service, HW-35174. 19 pp.