THE ENERGY CONCEPT OF LIFE 17 



like the monads these interactions are very simple; in higher 

 organisms like man these interactions are elaborated through 

 physicochemical and other agents, some of which have already 

 been discovered although doubtless many more await discovery. 

 Thus we conceive of the origin and development of the or- 

 ganism as a concomitant evolution of the action, reaction, and 

 interaction of energy. Actions and reactions are borrowed 

 from the inorganic world, and elaborated through the produc- 

 tion of the new organic chemical compounds; it is the peculiar 

 evolution and elaboration of the physical principle of inter- 

 action which distinguishes the living organism. 



Thus the evolution of life may be rewritten in terms of in- 

 visible energy, as it has long since been written in terms of 

 visible form. All visible tissues, organs, and structures are 

 seen to be the more or less simple or elaborate agents of the 

 different modes of energy. One after another special groups of 

 tissues and organs are created and coordinated — organs for the 

 capture of energy from the inorganic environment and from the 

 life environment, organs for the storage of energy, organs for 

 the transformation of energy from the potential state into the 

 states of motion and heat. Other agents of control are evolved 

 to bring about a harmonious balance between the various or- 

 gans and tissues in which energy is released, hastened or ac- 

 celerated, slowed down or retarded, or actually arrested or 

 inhibited. 



In the simplest organisms energy may be captured while the 

 organism as a whole is in a state of rest; but at an early stage of 

 life special organs of locomotion are evolved by which energy is 

 sought out, and organs of prehension by which it may be seized. 

 Along with these motor organs are developed organs of ojfense 

 and defense of many kinds, by means of which stored energy is 



