I] OF MATTER AND ENERGY 15 



the chromosomes or the germ-plasm can never act as matter 

 alone, but only as seats of energy and as centres of force. And 

 this is but an adaptation (in the light, or rather in the con- 

 ventional symbolism, of modern physical science) of the old 

 saying of the philosopher: apxv l^P V 4>^o-i^ /uLaWov r?}? vXrjq. 



