Organs or tissues Skin Rats ~ Biijiri n 6 Shore birds - Rojoa Ratio of d/m/g d/m/g in thousands 9.2 6 6 0.94 17. 2 2 Liver 6 1.9 2 12 8.1 tract Lung 6 thousands 2 Muscle Bone Digestive d/m/g in n 19. 6 1.0 of shore birds 2.06 0.63 7.6 0.67 0.45 2.5 1.32 57. 2 to rats 0.86 7.04 0.87 Only in the activity of the digestive tract do the two forms differ by more than a factor of three, also the differences are not consistently in favor of either of the forms. Differences in activity levels between birds of different feeding habits were found. Average values for the shore birds of the Rojoa-Aaraanbiru area and those for the terns in the Aaraanbiru area are as follows: Organs or tissues Terns - Aareanbiru n d/m/g in Shore birds -Rojoa thousands n d/m/g in thousands Ratio of d/m/g of shore birds to terns Skin 2 1.1 3 17. 15.45 Bone 2 0.86 3 k.O 4.65 2 0.78 3 4S 5.77 6 2.1 9 Muscle 2 Liver Digestive tract 0.36 3 1.1 76. 3.05 36.18 Shore birds and rats appear to be more alike in relation to uptake of radioactive materials than do the shore birds and terns. It appears likely, however, that the shore birds and rats are different regarding retention of radioactive materials - 72 -