On the Motion of Growth. IX. A Scheme for Analysis of Experiments on Growth,Nutrition and Metabolism

Abstract

Summary

(1) Post-embryonic growth of common laboratory animals is governed, in accordance with the first of equations (l), by 4 fundamental properties of growth represented by the constants ρ, λ, κ, and E. (2) Rates of growth () are altered when any one, or suitable combinations of these parameters are changed by experimental means. In practice, however, the problem is more likely to be the converse of this: which parameters are changed when the normal or control rate of growth is known to have been altered? Such a problem is insoluble so long as observations are limited to measurements of change in size, x, alone. (3) Heat production “during growth” ( ≠ 0 ≠ ) is quantitatively different from heat production when growth is in the stationary state ( = = 0). Heat production per unit time per unit mass is synonymous with metabolism, and the latter is dynamically related to growth via the properties represented by ρ and E _c. (4) The values of all constants along with their P.E.'s can be computed from simultaneous data on growth and metabolism. (5) The effect of any foodstuff, or of any procedure that influences growth can therefore be estimated in terms of the control values ρ_o, λ_o, κ_o and (E)_o, and the substances themselves may be compared by means of the respective changes induced in these four fundamental parameters of state.