246 N. W. Shock 



capacity for concentrating specific substances, such as PAH, in 

 tissue slices removed from the kidneys of animals of different 

 ages. It is thus apparent that a great deal of research re- 

 mains to be done before we can interpret age changes in renal 

 physiology. 



REFERENCES 



Barrows, C. H., Jr., Yiengst, M. J., Shock, N. W., and Chow, B. F. 



(1957). Fed. Proc, 16, 7. 

 BiLLis, L. DE (1954). Boll. Soc. ital. Biol, sper., 30, 370. 

 Brandfonbrener, M., Landowne, M., and Shock, N. W. (1955). 



Circulation, 12, 557. 

 CoHN, J. E., and Shock, N. W. (1949). Amer. J. med. Sci., 217, 388. 

 Gibson, J. G., II, and Evans, W. A., Jr. (1937). J. din. Invest., 16, 317. 

 Hamilton, J. A., and Shock, N. W. (1936). Amer. J. Psychol., 48, 467. 

 Herbeuval, R., Cuny, G., and Manciaux, M. (1954). Pr. med., 62, 



1555. 

 Hilton, J. G., Goodbody, M. F., Jr., and Kruesi, O. R. (1955). J. 



Amer. geriat. Soc, 3, 697. 

 Lewis, W. H., and Alving, A. S. (1938). Amer. J. Physiol, 123, 500. 

 Lippi, B., and Malerba, G. (1955). Arch. E. Maragliano, 11, 839. 

 McDonald, R. K., Solomon, D. H., and Shock, N. W. (1951). J. din. 



Invest., 30, 457. 

 Miller, J. H., McDonald, R. K., and Shock, N. W. (1952). J. Geront., 



7, 196. 

 Miller, J. H., and Shock, N. W. (1953). J. Geront., 8, 446. 

 Moore, R. A. (1931). Anat. Rec, 48, 153. 

 Shock, N. W. (1952). In Cowdry's Problems of Ageing, p. 614, 3rd ed., 



ed. Lansing, A. I. Baltimore: Williams & Wilkins. 

 Shock, N. W. (1956). Bull. N.Y. Acad. Med., 32, 268. 

 Shock, N. W., Watkin, D. M., and Yiengst, M. J. (1954). Fed. Proc.y 



13, 136. 

 Shock, N. W., and Yiengst, M. J. (1948). Fed. Proc, 7, 114. 

 Shock, N. W., and Yiengst, M. J. (1950). J. Geront., 5, 1. 

 Smith, H. W., Goldring, W., and Chasis, H. (1938). J. din. Invest., 17, 



263. 

 Videbaek, a., and Ackermann, P. G. (1953). J. Geront., 8, 63. 

 Watkin, D. M., and Shock, N. W. (1955). J. din. Invest., 34, 969. 



DISCUSSION 



Zweymiiller : One of the interesting things in your paper, Dr. Shock, 

 was this tendency for the glomerular filtration rate, Tnip^n and Tmo to 

 fall, which leads to the conclusion that the total number of nephrons is 

 diminished. Are the nephrons which are left, and particularly the 

 tubules, still able to elevate their function? Under normal physio- 

 logical conditions we have a Tmp^H» which means that under normal 



