oo presenta. studyof its length nts along ong. Sechese seg. st 33-mm ck back. posed to | Table Fie. 49-—Values for area and perimeter are for the bone shown in Figure 48 that the biopsy sample is taken from the samesite as the control samples. REFERENCES 1. Barer, M. and Jowsey, J. Bone Formation and Resorption in Normal Human Rib. Clin. Orthoped. 62, 241-247, (1967). 2 frost, H. M, Measurement of TIuman Bone Formation by Means of Tetracycline Labeling. Can. J. Biochem. Phusiol. 41, 31-42 (1963). u. Seddin, E. D., Frost, H. M., and Villanueva, A. R. Variatious in cross-section area of rib cortex with age. J. Gerontal, 18, 9-13 (1963). .Sedlin, E. D., Villanueva, A. R., and Frost, H. M. Age Le different ‘al densi. surfaces ‘th using was the surface rom the over the a film. A ere, (7) " micron at the isting to the cormber of ertebral ibeculaOss secperimeven in listed. ‘Aen at 1’, cadmium erent e the aken iples been very is im sure 201-205 (1963), 5. Hodges, 1). Applied Mathematics Division Tech. Memo No. 61 (1963). §. Llovd, E., Marshail, J. W., Butler, J. W., and Rowland, R. EL A Computer Programme for Automatic Scanning of Attoradiographs and Microradiographs of Bone Sections, Nature 211, 661-662 (19660). 7. Liovd, E., Rowland, R. E., Hodges, D., and Marshall, J. H. Surface-to-Volume Ratios of Bone Determined by Computer Analysis of Microradiographs. Nature 218, 365-6 (1968). CONCENTRATIONS OF TRACE ELEMENTS IN GREAT LAKES FISHES* iumber 1. F, Lucas, Jr., D. N. Edgington, and P. J. Colbyt nge to te area imeter The concentration of up to 14 trace elements has rea Is been determined in whole fish and fish liver samples re the obtained from Lake Michigan, Lake Superior, and point Luke Erie. The mean concentrations in 19 whole fish ‘P/A) simples from three species of fish were as follows: ‘ained wanium (8ppb), thorium (6ppb), cobalt (28 ¢ and Variations in the Speeifie Surface of Howship’s Lacunae as an Index of Human Bone Resorption. Anat. Rec. 146, (94ppb), arsenic (16ppb), chro- 1: im (1 ppm) and copper (1.3 ppm). The mean con‘utration of 40 liver samples from 10 species of ish were as follows: uranium (~2 ppb), thorium (S2ppb), cobalt (40 ppb), copper (9ppm), zine (80 ppm), bromine (0.4ppm), arsenic (80 ppb), and ctdmium (0.4 ppm). In addition, the following eleAbstract of paper presented at the Twelfth Conference on (cr Lakes Research, Ann Arbor, Michigan, May 1969, and * ~-itted fer publication. ‘", S. Bureau of Commercial Fisheries, P.O. Box 640, Ann or, Michigan, ments were observed in most of the samples: antimony (5-100 ppb), gold (2-5 ppb), lanthanum (1-20 ppb), rhenium (0.5-5 ppb), rubidium (0.06-4 ppm), and selenium (0.1-2 ppb). Variations in trace element concentration with species and collection site have been found. Uranium and thorium content varies with species, but not for the same species from different lakes. The trace elements, copper, cobalt, zinc, and bromine, have a nearly constant concentration in all samples studied. In contrast, the concentration of cadmium, ar- senic, and chromium was interspecies and for some species interlake dependent. The neutron activation, radiochemical group separation, and computer processing of complex gamma-ray spectra technique has proved to be a powerful and rapid method for the analysis of many trace elementsinfish.