BIOCHEMICALLY IMPORTANT COMPOUNDS 193 



way dissymmetry develops within living organisms. It is true, 

 as W. Kuhn^^^ has already pointed out, that the simple laws 

 of dissymmetric synthesis are not sufficient to explain the 

 extremely high degree of optical purity found in protoplasm 

 and the constancy with which it is maintained throughout 

 innumerable generations of organisms. There can, however, 

 no longer be any doubt that particular antipodes are formed 

 in living things as the result of the presence of pre-formed 

 dissymmetric substances, especially dissymmetric enzymes. 

 Furthermore, this asymmetry is enhanced by the character- 

 istic specific organisation of protoplasm which we shall discuss 

 in more detail later on. 



This explanation of the appearance of dissymmetry in 

 protoplasm does not, however, get over the problem of the 

 original dissymmetric synthesis, for all the syntheses discussed 

 so far have depended on the presence of pre-formed dis- 

 symmetric compounds which are usually derived from plants 

 (e.g. brucine and quinine). 



This question was raised very pointedly by F. R. Japp^''" 

 at the turn of the century. In his paper Stereochemistry and 

 vitalism Japp categorically denied the possibility of primary 

 dissymmetric synthesis and declared that optical activity 

 could only arise with the help of the ' life force '. Like a 

 living being, an optically active molecule can only arise 

 from another of the same kind. Dissymmetry never arises 

 primarily outside a living organism. 



This assertion turned out to be untrue, in that dissym- 

 metric substances can arise, not only in the presence of other 

 dissymmetric substances, but also under the influence of 

 dissymmetric physical factors. As we have already pointed 

 out, Pasteur^" had already had this very idea. He considered 

 that the formation of optically active compounds in nature 

 occurred under the influence of ' dissymmetric forces ' asso- 

 ciated with the movement of the Earth, terrestrial magnetism, 

 etc. With this in mind Pasteur tried to obtain optically active 

 substances by carrying out reactions in rapidly rotating tubes 

 or by allowing racemic mixtures to crystallise in a strong mag- 

 netic field. Pasteur did not obtain positive results by these 

 experiments. It was shown later by P. Curie"^ that this lack 

 of success was due to the fact that the influences applied by 



13 



