|.f>4 Beard, On the Occurrence of Dextro-rotatory Albumins in Organic Nature. 



lock and key in order to be able to exert a chemical action upon 

 each other. This conception has certainly gained in probability 

 and in value for stereochemical investigation since the phenomenon 

 itself has been transferred from the biological to the purely chemical 

 region. It forms an extension of the theory of asymmetry, but 

 without being a direct consequence of it, for the conviction, that 

 the geometrical build of the molecule even in looking-glass image 

 forms should exercise so great an influence upon the play of the 

 chemical affinities could, in my opinion, be gained only by new 

 observations founded on fact. The experience hitherto, that the 

 salts composed of two asymmetrical compounds may differ in 

 solubility and melting point would certainly not suffice for it. That 

 the fact established now for the complicated enzymes will also 

 soon be found for the more simple asymmetrical agents I doubt 

 as little, as the usefulness of enzymes for the ascertaining of the 

 configuration of asymmetrical substances. 



The experience, that the efficacy of the enzymes is restricted 

 in so high a degree by the molecular geometry, ought also to be 

 of some use for physiological investigation. But still more important 

 for this appears to me the proof, that the difference previously 

 accepted between the chemical agents in respect of molecular asym- 

 metry does not in fact exist. Thereby the analogy emphasized 

 more especially by Berzelius, Liebig, and others of 'living and 

 lifeless ferments' is again set up in a not unessential point 3 )." 



The third memoir, by Prof. Emil Fischer, is a summary of 

 the chief points of the two earlier ones, and in it (p. 81) under 

 the heading "Theoretical Considerations" the author writes: "But 

 the enzymes are quite especially valuable, as I first emphasized, 

 as means of recognition of stereochemical differences, and with 

 this I come back to the object, which I consider to be the most 

 important result founded upon fact of my experiments. These 

 furnish the unchallengeable proof, that of two molecular looking- 

 glass-image forms the one is broken up by enzymes under the same 

 conditions, under which the other remains intact. For this there 

 are two examples, the behaviour of /3-methyl-d-glucoside (plus) and 

 of /?-methy 1-1-glucoside (m i n u s) towards e m u 1 s i n , and the behaviour 

 of a-methyl-d-glucoside (plus) and of a-methyl-1-glucoside (minus) 

 towards the enzyme of yeast." On p. 82 "The ground of these 

 phenomena lies in all probability in the asymmetrical build of the 

 enzyme-molecule. For although these substances are not yet known 

 in pure form, their similarity to the proteid stuffs is yet so great 

 and their origin from these latter so probable, that undoubtedly 



3) Fischer, Emil. ,,Einfluss der Koufiguration auf die Wirkung der En- 

 zyme", in: Ber. d. d. chem. Gesellsch., V. 27, p. 2985-2993, 1894. 



