PRINCIPLES AM) DEFINITIONS 17 



on llie basis of what is known on chemical structure, wliieh 

 isomer of fructose presents the same position for the tifth 

 carbon atom as rf-glucose, one finds that it is laevorotatory 

 fructose. Thus d (+) glucose and d (-) fructose possess 

 the same relative configuration in spite of their rotation 

 in opposite directions. Both these isomers are found in 

 living organisms and belong to the same *' biological 

 series." 



Wohl and Freudenberg (1923) proposed to take glycer- 

 ine aldehyde and not glucose, as a standard of comparison, 

 conventionally considering the dextrorotatory form as a 

 member of the <7-series and attributing to it such a struc- 

 ture that the hydroxyl of the fifth carbon atom be again 

 written to the right. 



SUMMARY 



1. Dissymmetry is the property of molecules of possess- 

 ing non-superposable mirror-images. Dissymmetric mole- 

 cules can exist in two forms, right and left. 2. Asymmetry 

 is the property of molecular aggregates of presenting a 

 predominance of the right or the left form of dissymmetric 

 molecules. 3, Optical asymmetry is to be distinguished 

 from geometrical asymmetry. 4. Optical activity is at- 

 tributed to the spiral arrangement of atoms, either in 

 entire crystals, as in quartz, or in single molecules, as in 

 some organic compounds. 5. If, besides the sign of the 

 optical rotation of a substance, one considers the config- 

 uration of its molecules, one can classify the optical isomers 

 into "biological series" as found in living organisms. 



BIBLIOGRAPHY 



BEAGG, W., Proc. Boi/. Soc. A., 89, 575, 1913; IM, 405, 1925. 

 EERERA, G., Nature, 58, 616, 1898. 

 FINDLAY, A., Nature, 140, 22, 1937. 



FISCHER, E., Ber. cliem. Ges., ^7, 3189, 1894; 3^, 3638, 1900. 

 FRESNEL, A., Bull. Soc. Philomat., p. 147, 1824. 

 GAY-LIJSSAC, L., Couvs de Chimie, Paris, 1828. 

 JAPP, F. R., Nature, 58, 452, 1898. 



JUNGFLEISCH, M. E., Bull. Soc. Chim. Paris, 41, 222, 1884. 

 LOWEY, T. M., Optical Eotatoiy Power, Longmans, Green & Co., Loudon, 

 1935. 



