28 LOUIS PASTEUR. 



It is, therefore, true to say that the products of 

 inorganic nature, whether mineral or artificial, have 

 never yet presented molecular dissymmetry. It may 

 also be affirmed that the substances which exert the 

 greatest influence in vital manifestations, which are 

 present and active in the seed and in the egg at the 

 moment of the marvellous start of animal and vege- 

 table life, all present molecular dissymmetry. 



Would it be possible to indicate a more profound 

 distinction between the respective products of living 

 and of mineral nature, than the existence of this 

 dissymmetry on the part of the one and its absence 

 on the part of the other ? Is it not strange that not 

 one of these thousands and thousands of artificial pro- 

 ducts of the laboratory, the number of which is each 

 day augmented, should manifest either the power 

 of turning the plane of polarisation or non-super- 

 posable dissymmetry? No doubt natural dissym- 

 metric substances gum, sugar, tartaric and malic 

 acids, quinine, strychnine, essence of turpentine, 

 &c. may be employed in forming new compounds 

 which remain dissymmetric, though they are artifi- 

 cially prepared ; but it is evident that all these new 

 products do but inhejit the original dissymmetry of 

 the substances from which they are derived. When 

 chemical action becomes more profound, all dissym- 

 metry disappears, and is never seen to reappear in the 

 successive ulterior products. 



