The Origin of Life 23 



the proteins required for the formation of the material 

 of a growing animal. ' 



3. The essential difference between living and non- 

 living matter consists then in this: the living cell syn- 

 thetizes its own complicated specific material from 

 indifferent or non-specific simple compounds of the 

 surrounding medium, while the crystal simply adds 

 the molecules found in its supersaturated solution. 

 This synthetic power of transforming small "building 

 stones" into the complicated compounds specific for 

 each organism is the ''secret of life" or rather one of 

 the secrets of life. 



What clew have we in regard to the nature of this 

 synthetic power? We know that the comparatively 

 great velocity of chemical reactions in a living organism 

 is due to the presence of enzymes (ferments) or to 

 catalytic agencies in general. Some of these catalytic 

 agencies are specific in the sense that a given catalyzer 

 can accelerate the reaction of only one step in a com- 

 plicated chemical reaction. While these enzymes are 

 formed by the action of the body they can be separated 

 from the body without losing their catalytic efficiency. 

 It was a long time before scientists succeeded in isolat- 

 ing the enzyme of the yeast cell which causes the alco- 

 holic fermentation of sugar; and this gave rise to the 



^ This fact was thoroughly established by Mendel and Osborne. A 

 summary of their work is given in Underhill, F. P., Physiology of the 

 Amino Acids, 1916. 



