GROWTH IN TIME OF THE TOTAL ORGANISM 



213 



(0) Equifinality of growth 



An important consequence of the growth laws discussed is the equifinality 

 encountered in animal growth. 



It is well known and frequently found that the same species-characteristic final 

 size may be reached J, after temporary suspension of growth, and 2, from different 

 initial sizes at the start. The first applies to cases when diet was temporarily 

 insufficient in quantity, vitamins, etc.; there are, in particular, many experiments 

 on rats showing this effect (Kopec, 1938; Clarke and Smith, 1938; Jackson, 1939, 

 etc.) (Fig. 20). The second holds true in litters of varying size: in large litters 

 weight at birth of the newborn is lower, but the same final weight is eventually 

 reached in animals both large and small at birth (Kopec, 1932). Naturally this 

 equifinality of growth only prevails if no lasting damages {e.g. of bone growth in 

 humans) remain after the period of malnutrition. 



200 



150 



£100 



50 



25 50 75 100 125 150 175 



200 225 250 

 Time in days 



275 300 



Fig. 20. Equifinality of growth. Heavy curve: normal growth of rats. Broken curve: at 

 the 50th day, growth was stopped by vitamin deficiency so that there was no increase but 

 only maintenance of the body weight. When normal regime was re-established, the animals 

 reached the normal final weight, growth rates approximating values corresponding to 

 body size, not to age. After Hober from Bertalanffy, 1951a. 



Equifinality appears to be paradox if it is envisaged from the conventional 

 causal viewpoint; for it appears as if events were determined by states to be 

 reached only in the future. Nevertheless equifinality is a general characteristic of 

 open systems in so far as they approach a steady state (p. 146). In such systems, in 

 contrast to conventional closed systems, the time-independent final state is not 

 determined by the initial conditions but only by the system parameters of 

 transport and reaction. Hence, the final state is independent of the initial state 

 as well as of the course the process has taken. It can easily be seen that any process 

 of growth described by equation (5.16), except for the case m — n = i [i.e. growth 

 according to types I or III), must show the property of equifinality. 



Further it follows from theory that growth rate is not a function of time, i.e. does 

 not automatically decrease as age increases, but rather is a function of the body size 

 reached. Hence, after an inhibition is lifted, growth is resumed at a rate which 

 corresponds to body size and not to age (Fig. 20). In a similar way, specific growth 



Literature p. 253 



