SUBSTANCES INACTIVE THROUGH LOSS OP DISSYMMETRY 37 



remote, and therefore as a contingent, but the fact that 

 the idea of this correlation has given us, through Pas- 

 teur, the idea of the dissymmetrical structure of the 

 molecule, suffices to make it beneficial, whether false or 

 true. 



Here we have, in reality, the idea which has come forth 

 from it quite naturally, like the grain from the ear: a 

 molecule which possesses the rotary power is dissym- 

 metrical. But a dissymmetrical molecule cannot be 

 contained in one plane because this plane would be for 

 it a plane of symmetry. Therefore, the molecule must 

 form in space a geometrical solid of three dimensions. 

 That is the first conclusion. Here is another: as we are 

 familiar with the number and nature of atoms entering 

 into the molecule we may attempt to arrange them in 

 such a way that the dissymmetry of the solid which they 

 form corresponds to the direction of the rotary power of 

 the molecule. Summed up, such is the series of deduc- 

 tions drawn nearly simultaneously in France by Le Bel, 

 in Holland by Van-t-Hoff, and which have served to 

 found a new science, stereo-chemistry, of which Pasteur 

 is thus the forerunner. 



Let us forget, then, all the false interpretations of this 

 memoir on aspartic acid, and note only the certainty 

 with which Pasteur, arrested by a conception, inexact in 

 the case to which he applied it, but the general justness 

 of which the future was to confirm, succeeded in tracing 

 a fourth plan of construction for an active molecule. 

 "We are here," he would have been able to say at this 

 moment, " thanks to the discovery of inactive substances, 

 in possession of a fertile idea. A substance is dissym- 

 metrical, right or left: by certain artifices of isomeric 

 transformations, which must be sought and discovered for 

 each particular case, it can lose its molecular dissym- 

 metry, be twisted, to use a rough comparison, and effect 



