315 



Since the experiments of Marckwald and Paul, which 

 are in some respects perhaps comparable with those mentioned here, 

 never has the remarkable analogy of specific enzyme-action, and 

 that of much more simply built catalysts such as quinine, quinidine, 

 etc., been brought to the fore in such a striking way. Beyond 

 all doubt we have to deal in both cases with the unequal velocities 

 of decomposition of the compounds formed intermediately between 

 the two antipodes and the accelerating, dissymmetrical catalysts. 

 If only the ratio of both velocity-constants be supposed to far 

 surpass unity, the one-sidedness of enzyme-action will now be fully 

 conceivable, as there is an equilibrium between the free acids and 

 bases and the salts formed by their combination, and as the 

 quantities characteristic of the state of equilibrium are inversely 

 proportional to the constants of the reaction-velocities of both 

 opposite reactions. It follows that the specificity of the enzyme- 

 arid ferment-action is really of a quantitative, rather than of a 

 qualitative nature, it being founded on an appreciable difference 

 in reaction-, or rather in decomposition-velocity of the interme- 

 diately formed combinations between the substance attacked and 

 the dissymmetrical, catalysts. 



11. After all that has been done hitherto in this field of 

 research, we can, therefore, safely claim to have a much clearer 

 insight into the significance of the one-sided synthesis of the 

 living organism. The occurrence of optically active substances 

 during that synthesis in living bodies, finds its explanation in 

 the fact that natural synthesis can never lead to a state of 

 completed chemical equilibrium, the produced substances being 

 continuously withdrawn from and used by the organism to suit its 

 physiological needs. In connection with the fact that such chemical 

 processes commonly proceed in several stages which cannot represent 

 states of complete equilibrium, but are only consecutive steps in 

 the whole chain of events, the apparent contrast between 

 natural and artificial synthesis is explained by the mere fact that 

 no highest degree of mechanical stability, and therefore no highest 

 degree of symmetry, can be expected in the synthesis performed 

 by the living organism. In natural synthesis rather a preference 

 appears for the formation of metastable intermediate products, 

 because the whole process of life is based upon the instability of 

 the conditions of the moment, and on the possibility of their uninter- 

 rupted change. Metastable products generally act much more ener- 



