The variance in density of mineral-plus-protein has the form to Csi [adele—NT 2 2 12, Pacé, N. and Rathbun, E. N., Studies on body composition. II]. The body 13. 14, while the variance in f, after substituting for a , becomes ‘ ddy = \* ¢ ajd, —de)? 2 a = ( : ) ou + Chia. —d)i** d, ~dy? Frcwbuat hee Sertet aa 0.308 7 (te— ay) dy dy ~ dy 667-676 (1945). 16, \% 4 19, It is a pleasure to thank Dr. John H. Lawrence and Dr. Hardin B. Jones for their support in the course of this and related investigations. The author is also indebted to Capt. A. R. Behnke and Dr. J. Brozek for their suggestions and discussions on the subject. The material presented here is based upon work performed under the auspices of the U.S. Atomic Energy Commission. of body fat by means of the body specific gravity, J. Biol. Chem., 158, 15. Siri, W. E., An Apparatus for Measuring Human Body Volume, Univ. Calif. Rad. Lab. Report 228 (196h). oa") Acknowledgments water and chemically combined nitrogen content in relation to fat content, J. Biol, Chem, 158, 685-691 (1946). Pitts, G. C., Body fat accumulation in the guinea pig, Am. J. Physiol., 185, 41-48 (1956). Rathbun, FE. H. and Pacé, N., Studies on body composition. I, Determination Siri, W. B., Advances in Hiological and Medical Physica, 1V, Ed. C. A, Tobias and J. H. Lawrence, The Academic Press, N.Y. (1956). Siri, W. E., Joiner, FE. E., Stratton, R. R., and Taylor, J., Studies of total body water, density, and blood volume of 300 random normal persons representing a highly heterogeneous group in body composition. To he published, Spray, C. M. and Widdowson, E. M., Effect of growth and development on the composition of mammals, Brit. J. Nutrition, 4, 332-353 (1950), Stern, H., Investigationa on corporeal specific gravity and on the value of the factor in physical diagnosis, M. Rec., 59, 204-207 (1901). 20, Widdowson, E, M., McCance, R. A., and Spray, C. M., The chemical composition of the human body, Clin. Sef., 10, 113-126 (1961). References i] sequent systematizationa, Ann. N. ¥. Acad. Sci., 56, 1095-1142 (1953). Behnke, A. R., Body composition. I, In vive estimation of fat and water content from specific gravity (density) determinations, Symposium on Methods for Evaluation of Nutritional Adequacy and Status, Nat. Acad, Sci.-Nat. Res. Council, Washington, 204-313 (1954). Behnke, A. R., Feen, B. G., and Welham, W. C., The apecific gravity of healthy men, J. Am. Med, Aasnoc., 118, 495-498 (1942). Rehnke, A. R., Osserman, E. F., and Welham, W. E., Lean body mass, A.M. A. Arch. Inter. Mod., 91, 585-601 (1963). Brekhus, P. J. and Armstrong, W. D., A method for the separation of enamel, dentin, and cementum, J. Dent, Rea., 15, 23-29 (19365). Brokek, J., Changes of body composition in man during maturity and their nutritional implications, Fed. Proc, 11, 784-793 (1952). Forbes, R. M., Cooper, A. R., and Mitchel, H. H., The composition of the adult Wee body as determined by chemical analysis, J. Biol, Chem., 203, $59- 366 (1058). Haurowitz, F., Chemistry and Biology of Proteins, The Academie Preas, N.Y. (1950), 10. 11. Keyoa and Broek, J., Body fat in adult man, Physiol. Rev., 33, 245-325 3). Mitchell, H. H., Hamilton, T. S., Steggerda, F. R., and Bean, H. W., Chemical composition of the adult human body and its bearing on the biochemistr y of growth, J. Htol. Chem., 158, 625-637 (1945). Morales, F. and Williams, A. R., Calculation of body composition, J. App. Physiol, 12, 225-229 (1958). 243 244 YSSW1D INSTTOUV LAI NOEDLRLEIN 16b €661 YAPOLDIOMAYUWALAS ‘¢ (ON 6 “IOA NOLLRLLIN Behnke, A. R., The relation of Jean body weight to metabolism and some con-