The Origin of Organic Molecules 7 



this kind are all unstable with respect to the completely oxidized and 

 reduced condition. Thus at 25°C the following reactions all proceed 

 toward the right-hand side. 



4CH 3 OH -» 3CH 4 + C0 2 + 2H L ,0 



2CH 2 -» CH 4 + CO, 

 4HCOOH -> CH 4 + 3C0 2 + 2H L 



At least for many other carhon compounds, similar statements are true. 

 Compounds of carhon in intermediate oxidation states such as those 

 common in living organisms are unstahle even in the ahsence of hy- 

 drogen or oxygen. It is also true that even small pressures of hydrogen 

 will lead to reactions to produce the completely reduced state of 

 carhon, and that no carhon dioxide would he produced. Also oxygen 

 will burn up all these compounds at ordinary temperatures, given 

 sufficient time with or without suitahle catalysts. What we note is that 

 the compounds of which living organisms are composed are unstahle. 

 This is necessarily true, for otherwise no metaholism in either fer-. 

 mentative or oxidative organisms would occur. But this emphasizes 

 that during the evolution of the most primitive living organism, as 

 well as during the lives of well-organized living things, a continuous 

 and effective source of energy must he present. 



We can estimate the sources of energy availahle today with some 

 precision, as listed in Tahle 3. Certain of these can be eliminated 



Table 3. Present sources of energy averaged over 

 the earth 



c Energy, 



source , % , 



cal cm " yr 



Total radiation from sun 260.000 

 Ultraviolet light 



\< 2,500 A 570 



\ < 2.000 A 85 



\ < 1.500 A 3.5 



Electric discharges 4 



Cosmic rays 0.0015 



Radioactivity (to 1.0 km depth) 0.8 



Volcanoes 0.13 



immediately from the list of effective supplies. Radioactivity is of no 

 importance now except that it may and probably does produce detri- 

 mental mutations as well as an occasional useful mutation. Potassium 

 exists in the bodies of all living organisms but its radioactivity sup- 



