BIOCHEMICALLY IMPORTANT COMPOUNDS 195 



of the sky is partly plane polarised but on reflection from 

 water it becomes elliptically polarised. Thus, many causes 

 work together to bring about the presence of right ellipti- 

 cally-polarised light on the surface of the Earth. 



Thus we now have some basis for supposing that the action 

 of circularly- or elliptically-polarised light (especially ultra- 

 violet light) must have led to the appearance of dissymmetric 

 substances in the atmosphere and hydrosphere of the Earth 

 even before the emergence of life. 



We must point out another possible way in which dis- 

 symmetric substances could have been formed without the 

 participation of living things, namely by using dissymmetric 

 crystals as catalysts. The possibility of using this method for 

 the synthesis of dissymmetric substances in the laboratory 

 was noted by I. Ostromisslensky^'^ as early as igbS. However, 

 it was not until the 1930s that this idea was realised practi' 

 cally in the experiments of G.-M. Schwab and his collabora- 

 tors'^^ and in the analogous experiments of A. Stankewitch.'"^ 

 G.-M. Schwab succeeded in obtaining an optically active 

 substance by partial destruction of its racemate in a reaction 

 catalysed by metals deposited in a thin coat on dextro- or 

 laevo-quartz crystals. 



Such quartz crystals are ^videly distributed in inorganic 

 nature. J. D. Bernal,'" therefore, put forward the hypothesis 

 that the dissymmetry of organic substances might have arisen 

 primarily, before life appeared on the Earth, as a result of 

 the synthesis of these compounds on the surfaces of quartz 

 crystals which adsorbed the starting materials. It is true that 

 in Schwab's experiments it was not synthesis but decomposi- 

 tion which took place. Recently, however, some Soviet chem- 

 ists, in the first place A. Terent'ev and his colleagues,"^ 

 have succeeded in carrying out the direct dissymmetric syn- 

 thesis of a number of organic compounds by using catalysts 

 deposited on powders made from crystals of dextro- or laevo- 

 quartz. From our point of view the most interesting reactions 

 are the aldol condensations and the reaction of cyanethyla- 

 tion, which occur by quartz catalysis in the liquid phase and 

 at ordinary room temperatures. 



In conclusion, we shall mention a few cases of the spon- 

 taneous development of dissymmetry from optically inactive 



