64 life's beginning on the earth 



In many cases these methods of chemical synthesis con- 

 sist in simply mixing and heating together the carbon com- 

 pounds which are to combine, just as iron and sulfur can 

 be heated together to make them combine. Yet in the 

 chemistry of carbon compounds not every two substances 

 will combine if heated together. Through his skill and 

 extensive experience, the chemist knows how to select those 

 that will react upon each other. In this way the study of 

 these carbon compounds has been developed into a highly 

 involved science whose methods are artificial, but whose 

 products are in many instances identical with those pro- 

 duced by life. 



4. HOW ARE CARBON COMPOUNDS MADE IN THE LIVING 



NATURE? 



How can we hope to advance further? How can we 

 understand the ways and means by which carbon com- 

 pounds are made in the living plant or animal? 



No one should say that this, the deepest hidden secret 

 of nature, cannot be revealed. Only a century ago the 

 generally accepted teaching was that no compound of plant 

 or animal origin would ever be made by artificial means. 

 How wrong has such a conception proved to be! Why 

 should we now be forced to stop halfway, even if serious 

 difficulties may retard further progress? Some of these 

 difficulties have recently been overcome: we can under- 

 stand Nature's gentle and efficient methods of making the 

 most complicated carbon compounds: such substances as 

 sugars, cellulose or proteins. Few of them can be made by 

 the forcible laboratory methods in which our research 

 chemists make use of strong acids, heat, and complicated 

 apparatus, working with a quite disproportionate expense. 

 Thus the ordinary cane sugar, selling a( a few cents a pound, 

 is literally worth its weight in gold when made artificially in 

 the laboratory. Nature performs such a difficult task with 



