203 



is no way to escape the urgency of this conclusion, and the only 

 question which may arise is: can we hope that further investigation 

 will enable us in future to remove this barrier? 



In the author's opinion the contrast may be only of an apparent 

 nature in so far, as the products of living nature do not possess the 

 character of systems of absolute mechanical stability. The restless 

 process of growth and metabolism in living nature, the never 

 stopped current of consecutive events in the chain of life-evolution, 

 is rather based upon a certain lack of mechanical stability of the 

 stages arrived at successively. Highest mechanical stability corres- 

 ponds, however, only to highest possible symmetry under existing 

 conditions; and only because in living nature no such perfect 

 mechanical stability can be reached, the direction of natural events 

 seems to be contradictory to this principle. We shall return to 

 these questions later. 



trical compounds exists, may be seen also in the case of the transition of 1-2-4- 

 chlovobenzene-disulphonic acid into the symmetrical 7-3-5-derivative ; in the same 

 way, if p-chlorobenzene-sulphonic acid be treated with strong sulphuric acid at 200 C, 

 the symmetrical I-3-5-derivative is formed in excess; cf. S. C. J. Olivier, Receuil 

 des Trav. d. Chim. d. Pays-Bas, 37, 307, (1918); 38, 351, (1919). 



In many polymerisation-processes: acetylene into benzene, cyano chloride and 

 cyanobromide into derivatives of cyanuric acid, etc., the increase of symmetry 

 undoubtedly plays an important part.. About the symmetrical structure of mixed 

 diazo-compounds, cf.: V. Meyer, Berl., Ber, 14. 2447, (1881); R. J. Friswell and 

 A. G. Green, Journ. Chem. Soc. London, 47, 924, (1885). Tentatives to elucidate 

 the part, which molecular symmetry plays with regard to many physical properties 

 of chemical compounds, have been made already on several occasions; thus, 

 e. g. with respect to the volatility of inorganic substances some indications are 

 given by O. Ruff, Ber d. d. Chem. Ges., 52, 1231, 1235, (1919). 



