INTERACTIONS 71 



tions. Thus in the origin of Hfe hydrogen and oxygen, ele- 

 ments unrivalled in chemical activity, functioned as ''attrac- 

 tive" agents to enable the life organism to draw in other chem- 

 ical elements to serve new purposes and functions. 



Through such attraction or other means the incorporation 

 of the active metals — ^potassium, sodium, calcium, magnesium, 

 iron, manganese, and copper — into the substance of living 

 organisms may have occurred in the order of their utility in 

 capturing energy from the environment and storing it within 

 the organism. For example, an immense period of geologic 

 time may have elapsed before the addition of magnesium and 

 iron to certain hydrocarbons enabled the plant to draw upon 

 the energy of solar light. This marked the appearance of 

 chlorophyll in the earliest algal stage of plant life. 



Evolution of Interactions 



The organism as a whole is made a harmonious unit 

 through interaction. Its actions and reactions must be regu- 

 lated, balanced, coordinated, correlated, protected from foreign 

 invasion, accelerated, retarded. This harmony seems in large 

 part to be due to the principle that every action and reaction 

 sends off as a by-product a "chemical messenger" which sooner 

 or later produces an interaction at some more or less distant 

 point. 



The regulating and balancing of actions and reactions within 

 the organism was provided for by the presence in the fluid cir- 

 culation of outside chemical agents, for many of the primordial 

 actions and reactions are known to give rise to chemical by- 

 products which circulate throughout the life organism. Among 

 such regulating and balancing influences we observe that ex- 

 erted by the phosphates upon the acidifying tendency of carbon 



