H. EYRING AND F. H. JOHNSON 5 



adsorption of a molecule onto the two atoms forming an unstable bond 

 could change an instability corresponding even to more positive free 

 energies than +2.6 kilo calories into a stable negative contribution to the 

 free energy. Our values, nonetheless, seem reasonable. We now must calcu- 

 late the total number of reactants of the type ni , whose concentration like 

 the other reactants we suppose to be 1/lOOOth molal. To make the calcula- 

 tion we suppose that there were enough pools to average 10^ liters per 

 square mile over the whole earth's surface. This gives, 



ni = TT X 8000- X 106 X (1/1000) 6.02 X 10--^ = 1.2 X lO"'^ molecules. 



We next suppose conditions yielding the above average values continued 

 over a period of a billion years. This gives 



dni/dt = 1/(10^ X 365 X 24 X 60 X 60) = (3.2 X lO^^j-^ 



Substituting these quantities into equation 2, we have 



(3.2 X lOi'^)-^ = 1.2 X 10^^ (1/1000) °>-i 



5.6 X 1012 (1/100) '"--e-=^«'Oo«/(-x=5««> (5) 



Equation 3 leads to m = 12 for the number of reactants combining to 

 form the critical complex. Now the value, m — 1 = 11, for the calculated 

 number of bonds that are made in assembling the critical complex from 

 reactants seems about right. 



Undoubtedly, as we gather more information, we will want to modify 

 the values of the various factors in our calculation of m, but the general 

 theory of a critical complex operating as outlined is almost a mathematical 

 necessity if we are to explain, within the framework of known physical 

 and chemical principles, the overwhelming abundance in all species of the 

 Z-amino acids. 



It is interesting that our theory, as expressed in equation 2, could be 

 tested. For example, one might be able to arrange conditions so that our 

 critical complex might appear in a reasonable time. Thus, if Ui were 

 taken as only a mole of molecules, i.e. 6 X 10--^ instead of 1.2 X 10^^, and 

 all concentrations of reactants were increased from 1/lOOOth to Vi molal, 

 spontaneous generation of our critical complex in accord with the other 

 values in S, using m = 12, would be speeded up by a factor of 4 X lO^'', 

 or it should occur about every nine days. It would be interesting to try 

 to find the proper concentrations of racemic molecules such that optical 

 activity accompanied as it would be by a great increase in viscosity would, 

 after an interval, suddenly appear spontaneously in a sterile system. 



When one considers the number of molecules ni that might occur from 

 broken cells in a living body and the probable concentrations of the 



