GROWTH IN TIME OF THE TOTAL ORGANISM 



199 



of these constants calculated from different growth curves should correspond to 

 the ratio of rates of resting metabolism (Oj consumption) of the organisms con- 

 cerned. The aquarium fish, Lebistes reticulatus (Guppy), is characterized by a 

 large sexual dimorphism in size, the females reaching double the length and a 

 multiple of weight of the males. Accordingly, a ratio of the constants t] i : i-f in 

 females and males is calculated from the growth curves (Fig. 10, p. 191). According 

 to theory, the rates of respiration in females and males also show a ratio i : i-f 

 (Fig. 8, p. 189) (Bertalanffy, 1938, 1941b). 



20 



10 

 SI 8 



w 6 



E 3 



30 50 70 100 200 500 700 



Weight in mg 



10 



0^ 



4 8 12 16 20 24 

 Time in weeks 



Fig. 18. Third metabolic and growth type: Planorbis sp. a Dependence of metabolic rate 

 on body size, b Growth curve (linear growth; diameter of shell). After Bertalanffy and 



Miiller, 1943. 



Regarding the catabolic constant (x) it follows from equations (5.28, 5.29, p. 191) 

 that the higher the value of this parameter, the faster the steady state is reached. 

 That is, an animal showing high catabolism of building materials (high protein 

 turnover) will grow fast, compared to one with sluggish turnover. This corresponds 

 to experience. Quantitatively, good agreement is found between the values 

 calculated from the growth curve and those determined in physiological experiment 

 (Table 11). In view of the simplicity of the model and the errors inevitable in 

 turnover determinations, the agreement is remarkable. For example, from the 

 growth curve of man a daily protein turnover of i . 1 65 g/kg body weight was 

 calculated (Bertalanffy, 1938), while determination with glycine marked with 

 ^^N gave a value of 1.3 g/kg body weight (Sprinson and Rittenberg, 1949a, b). 



Literature fi, zjj 



