HIS LITE AND LABOUKS. 181 



a very powerful twist on the plane of polarisation. 

 Quartz dissolved exerts no power at all. The mole- 

 cules of quartz, then, do not belong to the same category 

 as the crystal of which they are the constituents ; the 

 former are symmetrical, the latter is dissymmetrical. 

 This, in my opinion, is a very significant fact. By the 

 act of crystallisation, and without the intervention of 

 life, the forces of molecules, possessing planes of sym- 

 metry, are so compounded as to build up crystals which 

 have no planes of symmetry. Thus, in passing from 

 the symmetrical to the dissymmetrical, we are not com- 

 pelled to interpolate new forces ; the forces extant in 

 mineral nature suffice. The reasoning which applies 

 to the dissymmetric crystal applies to the dissymme- 

 tric molecule. The dissymmetry of the latter, however 

 pronounced and complicated, arises from the compo- 

 sition of atomic forces which, when reduced to their 

 most elementary action, are exerted along straight 

 lines. In 1865 I ventured, in reference to this subject, 

 to define the position which I am still inclined to main- 

 tain. 6 It is the compounding, in the organic world, 

 of forces belongirg equally to the inorganic that con- 

 stitutes the mystery and the miracle of vitality.' l 



Add to these considerations the discovery of Fara- 

 day already adverted to. An electric current is not an 

 organism, nor does a magnet possess life ; ' still, by 

 their action, Faraday, in his first essay, converted over 

 one hundred and fifty symmetric and inert aqueous 

 solutions into dissymmetric and active ones.* 



1 Art. ' Vitality,' Fragments of Science, 6th edit., vol. ii. p. 60. 



2 In Faraday 'a induced dissymmetry, the ray having once passed 

 through the body under magnetic influence, has its rotation doubled 

 instead of neutralised, as in the case of quartz, on being reflected 

 back through the body. Marbach has discovered that chlorate of 

 soda produces circular polarisation in all directions through the 

 crystal, while in quartz it occurs only in the direction of the axia. 



