- 32 - plant in which the Rongelap Island value was almost three times greater than for the other collecting areas. The corms had been washed and peeled to avoid contamination from the adhering soil. Since there is no evidence to indicate that the rate of uptake of radioactive materials should be higher at one island than another, and since the levels of activity in the soils at Rongelap Island varied considerably in two neighboring locations (from 1.7 uc/kg to 20 ue/kg), it is probable that the arrowroot at Rongelap Island was collected in relatively "hot" spots. In the early surveys it was found that the meter readings were highest in soil depressions and in pits such as those used by the natives for growing crops, and this may account for the values. During October 1955 the radioactivity in the soil was much higher than that in the plants, indicating a low rate of uptake. This seems to be corre- lated with the loss from the soil of those isotopes which are readily taken up by the plants. The ratio of soil/plant activity has increased from 8 to 190 in the period from March 1954 to October 1955. This would be true if there was a selective uptake of short. half-life fission products by the plants. It was also borne out by the radiochemical determinations, which showed that in addition to the rare earth isotopes, zr95 was the principa] source of radioactivity in the soil in March 19549, whereas it was Ru! in July 19555 Although Ru!8 comprised a relatively large fraction (23. 3%) of the activity in the soil, in most plants it was minor (7.8%). Much of the activity in the plants - up to 96 percent - was due to C3137 which comprised a very small part of the total activity in the soil (1. 17)®