1 86 



GROWTH 



PRINCIPLES AND THEORY 



is, O, consumption of tissues as measured by the Warburg technique (Qo^ = 

 (i.1 0-,/mg" dry weight/h.) shovild decrease with increasing body size; a similar de- 

 crease is to be expected in the concentration of respiratory enzymes and catalyzers. 



I. A considerable amount of work in this respect has recently been done. The 

 question is still somewhat controversial, but the statements to follow are a fair 

 presentation of available experience. 



In interspecific comparison of mammalian species of different sizes, ranging 

 from the mouse to the horse, a decrease of Qq^ with increasing body size is gener- 

 ally found (Kleiber, 1941 ; Weymouth, Field, and Kleiber, 1942; Weymouth et aL, 

 1944; Krebs, 1950; Martin and Fuhrmann, 1955). This decrease, however, is not 

 parallel in the various organs and, as a general rule, is less than would correspond 

 to the 3/4 power rule (p. 218) of metabolism. In a corresponding way, a decrease 

 with increasing body size was found in enzymatic systems connected with respira- 

 tion, such as in the concentration of glutathione (Gregory and Goss, 1933; 

 Patrusev, 1937), of cytochrome c (Rosenthal and Drabkin, 1943), of cytochrome 

 oxidase (Kunkel and Campbell, 1952), of succinoxidase and malic dehydrogenase 

 (Fried and Tipton, 1953). 



— Kidney 



Brain 



Liver 

 Heart 

 Lungs 

 Thymus 



~- Diaphragm 



8 10 



30 40 50 60 



80 100 200 



Body weight in g 



300 400 



Fig. 7. Q02 (1^1 02/'mg dry wt./h.) of rat tissues. Only the regression lines are reproduced; 

 for individual data and statistical analysis see original. After Bertalanffy and Pirozynski, 



1953- 



However, in intraspecific comparison, as between rat tissues from growing 

 animals of different body size and age, no systematic decrease of Qq^ paralleling 

 that of specific metabolic rate was found (Bertalanffy and Pirozynski, 1951, 1953; 

 Bertalanffy and Estwick, 1953). As Fig. 7 illustrates, no significant decline of 

 average Qq^ with increasing body size is found in brain, lung, and kidney; 

 a slight decline in skeletal muscle, liver, and heart; and a marked decline in the 

 diaphragm. Hence there is no systematic decrease of Qq^ ^^ the various organs 

 consistent with, and responsible for the decrease of weight-specific metabolic rate 

 with increasing body size. These results have been essentially confirmed by other 

 workers and with other materials such as liver and kidney in growing chicken 

 (Crandall and Smith, 1952); heart muscle of the guinea pig (Wollenberger and 



