Life: Its Nature and Origin 47 



Fig. 20. Individual and aggregated spherules formed by synthetic protenoid 

 in a hot solution of salt potassium thiocyanate. 1550 X. (After Fox.) 



cell-like spherules retained their individual integrity for several 

 weeks. 



When aspartic acid was heated alone or with other amino acids, 

 additional amino acids were formed through rearrangement of the 

 atoms of the original molecules. The simple organic compounds 

 malic or fumaric acid and their ammonium salts similarly converted 

 in part to aspartic acid. When malic acid was heated with urea, 

 the chief product was ureidosuccinic acid, one of the precursors of 

 nucleic acid. These are only a few of the many organic compounds 

 formed in the thermal experiments (Fox 1956, 1957). 



The basic biological staples such as amino acids, vitamins, pyrimi- 

 dines, and carbohydrates arise through steps involving the addition 

 of energy and the loss of water. Furthermore, the biological macro- 

 molecules such as proteins, nucleic acids, and polysaccharides arise 

 from these staples by exactly the same two processes. Both staples 

 and primitive types of biological macromolecules have arisen step- 

 wise in the thermal experiments. Hence, Fox believes that these 

 reactions may be the true original source of the primary ingredients 



