can be made by comparing the averages of the radioactivity of all the samples collected at each station. In Table 3 the average radioactivity of the algae at each coll ecting station is given. In the pre-test collection the samples from those islands close to, or upon which previous atomic tests had been con- ducted were the most radioactive. One sample in particular, collected in a stagnant pool 250 yards east of Lake George on Eberiru Island had a count of 54,000 d/m/g wet weight. Three others collected on the tide flats at the western ttp of Runit Island averaged 31,000 d/m/g. In the post shot series, for stations within 9 miles of the shot island (Bogallua, Engebi, Aomon), the average of all the algae samples from one station was not significantly different from a similar average for any other station. The samples collected at the islands beyond this area contained significantly less radioactivity, the least radioactivity being found at Japtan. Analysis by Species. Of the 7 most common species of algae collected there is no species shuwing activity which is consistently higher than that of any of the others. The radioactivity of the coralline algae, which contain a large amount of calcareous matter, does not adiffer from that of succulent forms for specimens at the same station. data are presented in Table 4. These When the samples were combined into phylogenetic groups still no difference in radioactivity between groups ceuld be shown. This observation was also noted in the 1949 survey report (AECD-3446). - 26 -