AND PERSONALITY 



diminished. How easily would the pack of wolves or dogs 

 run down and destroy these domestic animals that are 

 unadapted to the wild state. The size of the energy-con- 

 trolling organs would speedily change, and natural selection 

 would ultimately restore the energy-controlling organs of 

 the domestic animals to the state of those of their wild 

 ancestors. 



In the breeding and domestication of animals, use is 

 made of mutations to develop what is desired in the 

 domestic animal. When line breeding of these mutations is 

 carried to the extreme, the physiologic balance of the ani- 

 mal may be so stepped up in one organ or system that a 

 serious unbalance may occur in other organs or systems. 



It will be seen later that this principal of mutation plays 

 a role in the genesis of certain diseases in civilized man. 



161 



