102 HISTORY OF THE OCEANS 



influenced by those of Rubey (1955), but here I have less right to 

 talk than others more expert in physical chemistry. The point I 

 want to make later is that the precise composition of the early 

 atmosphere is not of decisive influence on theories of life, except 

 in one respect: the relative importance of photosynthesis at the 

 difi^erent stages of the evolution of life. If we start with less 

 energetic compounds, we need to evoke the energy of photo- 

 synthesis at an earlier period. 



The significant elements to be found on the primitive earth or 

 its hydrosphere, were essentially the simple ions of potassium, 

 sodium, magnesium, and calcium, a certain amount of phosphate, 

 though relatively little on account of its insolubility, as well as 

 iron and sulfur compounds, possibly reduced. These, according to 

 Henderson's principles, would be the natural basic materials which 

 would come together to make life possible. Certainly their special 

 properties, particularly the sulfydryl-sulfur and ferrous-ferric 

 oxidations and the coordinating power of transition elements such 

 as iron, cobalt, copper, and nickel, suggest that the first stages in 

 preparing the evolution of life were really in the nature of the 

 working out and combining of the properties of the substances 

 that were there at the outset. 



Now, a geological-geochemical system of the type I have just 

 described should be considered as approximately but not abso- 

 lutely in equilibrium. If it is in absolute equilibrium we would not 

 have to discuss at all problems like the origin of life — it would 

 have gone on indefinitely without any more complication. It is 

 only a slight trace of instability in the system that could lead in 

 one direction to the formation of more complicated compounds. 

 We have, in fact, two problems to face in the origin of life; the 

 first is how were the compounds which at present characterize life 

 first formed and by what stages; and the second, how did the 

 chemical mechanisms which we now recognize as metabolism 

 originate? In other words, we can ask ourselves how, within a 

 certain volume, self-contained chemical processes could be estab- 

 lished and balanced. This volume has to be conceived of as 

 essentially a volume in water and as at a more or less fixed and 

 rather low temperature. This is the essential physicochemical 



