46 Dynamic Evolution 



estimated at from five to ten per cent, of the 

 age of the animal at time of reproduction. 



We know that using an organ to perform 

 work concentrates energy in that organ so 

 that it improves in its capability of perform- 

 ing work. We also know that, within limits 

 which will be discussed later, the more an 

 organ is used the more energy will be con- 

 centrated. An athlete or a horse is trained 

 for a long time before he is fit for his trial of 

 strength and endurance. 



If, after an animal has been trained for a 

 considerable time, further concentration of 

 energy ceases by reason of the animal becom- 

 ing and remaining idle, the previously con- 

 centrated energy will dissipate in accordance 

 with the general law of the dissipation of 

 energy, and the animal will become weaker. 

 How much energy will be dissipated will 

 depend upon the degree of idleness, the length 

 of time the idleness continues, and the 

 nature of the concentration. 



The available energy in an animal is 

 measured by its volume and by its potential, 



