-2(mullet), suggesting that selection in favor of the non-fission 4sotopes was occurring in these animals. Kawabata (1954) reported the presence of the non-fission product zn°? in several organs and tissues of the albacore and big-eyed tuna, thus confirming the earlier postulate of Okano (personal communication to Kawabata), based on that zn? might be present. Subsequently this isotope was identified in several species of fish (Rinehart UWPL-43 1955; Yamada 1955; Mori and Saiki Yamatera spectra, VY et al., 1955; et al., 1955, 1956; Saeki, Okano, and Mori 1956; Yoshii et al., 1956; 1956; Nagasawa ‘etal., 1956) and in plankton (Seymour etal., 1957). In 1956 two additional non-fission product isotopes were | reported in biclogical samples: C00 by Weiss and Shipman (196 ) and Fe? by Amano et al., (1956). Amano and his co-workers also postulated the presence of Fe? on the basis of decay and absorption characteristics of the tron fractions. Yoshii (196) also suggested the presence of Fe? in fish samples and Kawabata (personal communication, paper in press) subsequently confirmed the presence of Fe? in contaminated fish, In 7Y spectra studies done by the present authors during the latter part of 1956 the presence of Zn 65 and Co? in many organisms was established; also the presence of Co?! , Coe, and Mn? in several samples was suggested. In the present study all of the above isotopes were identified. In addition Fe? and Feo? were found.