268 



all the investigations of the last decenniums, than it must have 

 appeared at the time when it was formulated by the great French 

 discoverer. In our opinion we may perhaps state these results in 

 the most concise way by summarising the typical features as 

 follows : 



/), An atomic arrangement in chemical molecules which has 

 only axial symmetry, involves the property of a possible fission 

 into enantiomorphously related isomerides endowed with optical 

 rotatory power. 



2). If a chemical compound possesses a single asymmetric 

 plurivalent atom (v ^> j) in the sense of Van 't Hoff and 

 Le Bel's theory, all conditions are present to make the com- 

 pound resolvable into such enantiomorphously related isomerides 

 endowed with optical rotatory power. 



j). The possibility of a fission as indicated is however not 

 necessarily restricted to the special case of the existence of 

 an asymmetric plurivalent atom; it is, contrary to this view, 

 merely dependent upon the presence of a stereometrical configura- 

 tion which has only axial symmetry, and this may also occur if 

 no asymmetric atoms whatever, in the sense of Van 't Hoff 

 and Le Bel's theory, be present. Reversely: even if several of 

 such asymmetric atoms be present in the molecule, it may 

 occasionally be optically wactive and wow-resolvable into enantio- 

 morphous antipodes. 



4). The magnitude of the optical rotation seems to be deter- 

 mined for a good deal more by the configuration in space, than 

 by the chemical contrast between the substitutes; the nature of 

 the plurivalent central atom however appears to be also of pre- 

 dominant significance therein. 



5). The non-superposable hemihedrism of the two antipodes in 

 the crystalline state, as postulated by Pasteur, is a phenomenon 

 which in most cases runs parallel to the occurrence of optical 

 rotatory power, but it is not always necessarily manifested 

 with it. It is undeniable that there is often a parallelism between 

 the two phenomena, but sometimes it may seem that there is no 

 such parallelism. The degree of non-superposable hemihedrism 

 seems to be chiefly dominated by the chemical contrasts between 

 the different substitutes, and perhaps has only an indirect relation 

 to the absolute magnitude of the optical rotatory power as 

 exhibited by the molecule in the dissolved state. 



