ORIGIN OF LIFE ON THE SHORES OF THE OCEAN 101 



the rate of liberation of water into the atmosphere through 

 volcanos, but nevertheless more rapid than the trapping of water 

 in sediments, so that there will be a net gain over the geological 

 periods and a continually deepening and probably also widening 

 oceans. The composition of this ocean will also be liable to change, 

 but, if it is also growing, the change will not be as much as it would 

 have been if the ocean had originally had its present volume. That 

 means that a smaller absolute amount of dissolved substances 

 would produce a greater concentration. The evidence, as I see it, 

 is that the present concentration of sodium chloride in the oceans 

 is relatively recent — the result of a progressive process of enrich- 

 ment. The early oceans may have contained less sodium, not only 

 relative to the water but also relative to the potassium. I base this 

 on indirect evidence from the potassium content of living organisms 

 which is high compared to ratios found in sea water. But, as will 

 be seen later, this may depend also on the relative absorptions of 

 sodium and potassium ions by clays. 



However, the major constituent which was liberated along with 

 the water into the early atmosphere must have been carbon 

 dioxide. It is argued that carbon dioxide is too oxidized a form to 

 be the basis of living structures and, indeed, there may be even 

 deeper down a certain amount of more reduced substances; the 

 presence of diamonds in the deepest pipes indicates that such things 

 do exist. Nevertheless, I believe that a spinel-like form of olivine 

 could contain carbon in place of silicon ; it would effectively be an 

 orthocarbonate, stable at high pressures, but one in which carbon 

 dioxide would be liberated by any movement which disrupted the 

 old complex or brought it nearer the surface. Some evidence of 

 this is furnished by the carbonatite rocks of very ancient origin. 

 The evidence from present day volcanos indicates that CO2 is the 

 major volcanic gas after steam, and only some of this is likely to 

 be of secondary origin derived from corals or limestones. This leads 

 me to modify the views expressed by Oparin and also by Urey as 

 to the composition of the early atmosphere, which I feel is likely 

 to have contained relatively little hydrocarbons, more carbon 

 dioxide, and a certain amount of ammonia or nitrogen produced 

 by its decomposition. In other words, my own views have been 



