Since the study began, tissue samples have been collected from three cows, two calves, and one fetus in October, 1973; three cows and two fetuses in July, 1974; one cow and two yearling calves in January, 1975; and two cows and two calves in January, 1976. Other animals sampled from the study area included three goats, three foxes, one jackrabbit, one coyote, and one yearling beef animal that wandered into the area in December, 1975. 2-year-old bulls are still grazing the study area. One aged cow and two Since the Nevada Applied Ecology Group meeting in May, 1975, analytical data have been received on all tissues collected through January, 1975. Much of these data were summarized and presented at the International Atomic Energy Agency/Energy Research and Development Administration symposium in November , 1975 (Smith et al., 1976). In January, 1976, an additional data printout was received from the analytical laboratory which included data on the gonads and four other tissues from five animals (three aged cows and two yearling bulls). The vital statistics of these animals are presented in Table 1. All animals grazed the outer compound of two compounds established in Area 13. The cows were sacrificed in July, 1974, approximately 14 months after their entry into the area. The bulls were sacrificed in January, 1975, 15 and 19 months after their birth within the outer compound. RESULTS AND DISCUSSION Table 1 also shows the data on the ash percentages of the tissues analyzed. Data are frequently expressed in reports as activity per unit of ash, or as per unit of dry weight, or as per unit of wet weight. Frequently there are wide variations in percent ash reported for similar tissues by the analytical laboratory, e.g., the gonads of cow number 4 and the femur of cow number 6 in Table 1. Also note the sixfold variation in other gonad data, fourfold in muscle, threefold in lung, and fourfold in liver. If the data are reported on these samples as activity per gram of ash, wide variation may result. Reporting the data as activity per kilogram of wet weight tends to level out these variations since water loss between sampling and analysis should not cause such a large variation. For example, if two muscle samples each weighing 2 kilograms (kg) and each containing 100 picocuries (pCi) of activity, are analyzed and the ash percentages are reported as 3 and 9%, then the activity per gram (g) of ash would be reported as 1.67 pCi/g ash and 0.55 pCi/g ash. This is a 300% difference. When these values are converted back to wet weight, the correct value of 50 pCi/kg is obtained. Also, dose estimates from ingestion of tissues require that the activity be expressed on a wet weight basis. Therefore, in the following discussion, all data are reported on the wet weight basis. 140