INTRODUCTION. xvii 



of a dissymmetric molecule is not a very precise one, 

 even in the mind of M. Pasteur. 



One word more with regard to the parentage of 

 preconceived ideas. M. Kadot informs us that at 

 Strasburg M. Pasteur invoked the aid of helices and 

 magnets, with a view to rendering crystals dissym- 

 metrical at the moment of their formation. There 

 can, I think, be but little doubt that such experiments 

 were suggested by the pregnant discovery of Faraday 

 published in 1845. By both helices and magnets 

 Faraday caused the plane of polarisation in perfectly 

 neutral liquids and solids to rotate. If the turning of 

 the plane of polarisation be a demonstration of mole- 

 cular dissymmetry, then, in the twinkling of an eye, 

 Faraday was able to displace symmetry by dissym- 

 metry, and to confer upon bodies, which in their 

 ordinary state were inert and dead, this power of 

 rotation which M. Pasteur considers to be the ex- 

 clusive attribute of life. 



The conclusion of M. Pasteur here referred to, 

 which M. Kadot justly describes as ' worthy of the 

 most serious consideration,' is sure to arrest the 

 attention of a large class of people, who, dreading 

 ' materialism,' are ready to welcome any generalisa- 

 tion which differentiates the living world from the 

 dead. M. Pasteur considers that his researches point 

 to an irrefragable physical barrier between organic 

 and inorganic nature. Never, he says, have you bean 



