viii Introduction 



becomes possible to experiment along different possible lines of prebiological 

 and chemical evolution. 



The series of fascinating essays gathered in this book provide a wealth of 

 ideas, data, and experiments on which to build a number of possible schemes 

 leading to organic molecules and from these to discrete organisms, from which 

 the first cells may have derived later. 



The chemical evolution of the surface of the primitive earth, and particularly 

 its organic chemical aspects, is clearly the main point of interest in our con- 

 temporary attitude towards the problem of the origination of terrestrial Ufe. The 

 interest in chemical evolution is made more pregnant by the possibiUty of know- 

 ing before long how chemical evolution is at present leading its course of events 

 in media not fundamentally different from the conditions which probably 

 reigned on the earth at periods anterior to the dawn of hfe. If mankind is 

 cautious enough not to modify the surface of the planets of the solar system by 

 thoughtless explosions or contaminations of any kind, a new field of dynamic 

 organic chemistry may be opened soon, and we may be able to study unsuspected 

 metaboUc cycles, the nature of which may bring in fresh ideas for the reconstitu- 

 tion of the possible ways of the chemical evolution of the Earth's surface before 

 the origination of Hfe in a reducing atmosphere. The hope of finding some forms 

 of primitive hfe in these sterile worlds, deprived of oxygen, appears remote, but 

 in our present ignorance great surprises may emerge from the study of samples 

 of the surface of the planets, soon to be taken off by man. We are entering an 

 age in which the study of chemical evolution and even of the origin of Ufe may 

 take the form not only of speculations based on induction and experimentation, 

 but also of a science based on actual observation. 



Marcel Florkin 



