ORIGIN OF LIFE ON THE SHORES OF THE OCEAN 105 



nitrogen, water, of fairly simple products such as those of the 

 amino acids, vegetable acids, possibly some hydrocarbons, and 

 carbohydrates. This problem has ceased to be an absolute block 

 to further advance since the classical experiments of Miller, 

 inspired by Urey. We now know, as this experiment has been 

 repeated with variations in many parts of the world, that from 

 almost any mixture of simple gases containing the elements 

 hydrogen, carbon, nitrogen, and oxygen and exposed to the kind of 

 exciting agents which are in plentiful supply on the surface of the 

 earth — sunlight, particularly ultraviolet not cut off by ozone, 

 lightning discharges, alpha, beta, gamma radiations from the 

 radioactive materials — will produce a mixture of these simple 

 molecular organic molecules. The proportion depends roughly on 

 the proportion of the original constituents, the more nitrogen, that 

 is, the more ammonia there is in the original constituents, the 

 larger number of amino acids, the less ammonia, the larger the 

 number of ordinary vegetable acids. Obviously, starting with a 

 system of low-energy state, that is, containing CO2, it will be 

 necessary to feed more free energy into it from the radiation than 

 if starting from a high-energy state involving methane. But the 

 end products are the same, and one of these days we shall under- 

 stand the process itself because, admittedly, now the experiment 

 shows only that the thing can be done, it has not shown in any 

 detail the processes by which it has been done. Unraveling it is 

 likely to be quite a complicated piece of physicochemical analysis. 

 Now we may consider the first stage to end with the production 

 of a number of molecules which will be more or less reduced, that 

 is, they will be carbohydrate or amino acids or hydrocarbons, but 

 in all cases they will be soluble in bulk in water, and this raises an 

 enormous problem at the second stage. Because as all such products 

 must come from the primitive atmosphere, which in bulk can only 

 have been a small fraction of the oceanic water, the concentration 

 there can never have been very large. The problem is how can 

 such molecules dispersed in sea water in concentrations of a few 

 parts per million come together sufficiently to produce a further 

 development? Now this process of the further concentration has 

 not been given, I think, sufficient consideration and I, myself, have 



