284 



stability. This very assumption has been the principle which led 

 to the discovery of our usual fission-methods by Pasteur. 



It must however be clear on closer examination that, properly 

 speaking, in these methods of fission we always make use, in the 

 last instance, of the phenomena of life, as manifested in the chemical 

 synthesis which occurs in the cells of animals and plants. If we 

 leave the method of fission by spontaneous crystallisation aside 

 for the moment, we can only use for our purpose: either the 

 combination of racemoids with the optically active acids or bases 

 which are isolated from plants or animals; or we make use of 

 the apparently selective action of ferments and enzymes which 

 also are only produced by living cells 



The living plant or animal, in striking contrast to what we 

 observe in our laboratory-experiments, seems to produce directly 

 from inactive materials such as carbon-dioxide, water, ammonia, 

 etc., the optically active substances which are met with in its 

 organism, unaccompanied by their optical antipodes. 



The majority of proteids are laevogyratory, the bile-acids dextro- 

 gyratory. Plants always produce the same optically active coniine, 

 nicotine, strychnine, etc., and the quantitative experiments of 

 Brown and Morris 1 ) on the formation of the carbohydrates 

 in plants seem to prove beyond doubt, that exclusively d-glycose 

 and d-fructose are produced in vegetable cells, not their laevo- 

 gyrate antipodes. The direct production of optically active sub- 

 stances seems to be the very prerogative of life therefore; and 

 the cases are extremely rare, where racemic compounds are met 

 with in the living tissues. 



An exception of this is found in the case of pinene, extracted 

 from the leaves of Myristica fragrans Htn, which, according to 

 Van Romburgh 2 ), sometimes is laevogyratory , sometimes 

 dextrogyrate, - - it being impossible to tell under what particular 

 circumstances the one or the other of the antipodes is produced. 



Neuberg 3 ) found, that an wactive pentose was execreted by 

 the human organism in some cases of so-called "pentosuria", - 

 which, however, according to af Klercker, is a mixture of the 



1) H. T. Brown and G. H. Morris, Journ. Chem. Soc. London, 63. 604. (1893). 



2) Private communication to the author by prof. P. van Romburgh. 



3) C. Neuberg, His-Engelmann's Archiv, Physiol. Abth., (1902), p. 544; 

 idem, Der Harn /. p. 370. (1911); Ber. d. d. Chem. Ges. 33. 2243. (1900). 



