300 



From this the impression is left that, notwithstanding the 

 enormous development of organic synthesis since the days of 

 Liebig and Wohler, there still remains a deep gulf between 

 natural and artificial synthesis. The plant, that mysterious and 

 highly complicated laboratory, produces from the simple inactive 

 constituents of the atmosphere and the soil, even within a very 

 limited range of low temper eatures, the necessary carbohydrates, 

 proteids, etc., in their optically active forms. 



"I know of no more profound difference than this between common 

 substances and those produced under the influence of life", - 

 Pasteur wrote again in 1860; and apparently he was quite justified. 



Natural, in contrast to artificial synthesis, thus appears to be 

 a strictly "one-sided" or "asymmetrical" synthesis, and, moreover, 

 also of a very exclusive nature. All attempts to isolate laevogyratory 

 glucose or fructose from plants, have hitherto failed l ), neither has 

 there been any success with any of the other optically active 

 products of vegetable or animal bodies. A living world, the 

 mirror-image of the one known to us, seems to be a grotesque 

 phantasy 2 ). What would be the consequences of an eventual sudden 

 inversion of all synthesis in plants and animals, as we now know 

 it? "What world would be presented to our eyes", - asks 

 Pasteur, "if the cellulose turned from a right-handed to 



a left-handed, the blood-albumine from a laevogyratory to a dextro- 

 gyratory substance?" Indeed, if such circumstances could be realised 

 in the living tissues, investigations of unlimited range would be 

 open to the future, and at present such questions are worthy 

 of the most careful attention of scientists. However, so far, we 

 can only state the rigorous and remarkable constancy of character 

 of the chemical world in plants and animals. The living world 

 is "specific" in its dissymmetry, and its dissymmetrical specificity is 

 of the highest degree. For Pasteur, chemical compounds of 

 one-sided dissymmetry could not arise, save under the influence of 

 life; and in this difference between artificial and natural synthesis, 

 the great master of natural science saw the most characteristic 



!) E. Fischer, Ber. d. d. Chem. Ges., 27, 3230, (1894). 



2 ) A case, however, in which at least dextro- and laevogyratory structures 

 seem to occur simultaneously in nature, was found by Delsman with Balanus 

 balanoides while in process of cleavage; cf. : H. C. Delsman, Tijdschr. der 

 Nederl. Dierk. Vereen., (2), 15, (1917). 



