-~4]- conditions are known to cause nutrient deficiencies which can sometimes be identified by the appearance of the plant. For example, nitrogen deficiency is often accompanied by yellowing and drying of the leaves and calcium deficiency is often followed by blackening and death of the plant (die-back). removed In coral atolls where the top soil has been the retention of rain water in the surface layer of soil would be slight, resulting in the curling, and ultimate death of the shallow-rooted plants. drying, On the basis of these observations it may be concluded that some of the abnormalities observed could have been caused by factors other than radiation. Therefore, it would be im- possible to ascertain all of the causes of damage to plants in an area where radiation and nutrient deficiencies both exist. In areas of high radiation levels, much of this damage could be attributed to the radiation, because it has been shown in controlled field experiments, with several plants, that chronic doses of gamma radiation of 13 to 37 r per day for two to five months can cause plant abnormalities of various kinds (12) | Similar to those found at the Eniwetok Proving Ground. The total gamma dose delivered in these ex- periments ranged from 780 r to 5550 r. In more recent studies 2