223 



is that by means of living organisms, by bacteria, moulds, yeasts, and 

 by a number of very complicated organic substances belonging 

 to the proteids, named ferments or enzymes. 



Pasteur 7 ), as is well known, was originally engrossed by the idea 

 that the production of single optically active substances was the 

 very prerogative of life. To this view of vitalism, which supposes 

 that in vital agency, special asymmetric forces play a directional 

 role, a number of experiments must be referred, made by him in 

 later years, and which were as unsuccessful as all other attempts 

 made since then by a number of chemists, to produce directly an 

 optically active substance from an inactive material by mere 

 chemical action. In the next chapter we shall return to these 

 interesting and fundamental questions in detail ; it suffices here to 

 point out the fact that, guided by this preconceived idea, Pasteur 

 started to investigate more accurately the action of various moulds 

 on solutions of calcium- and ammonium-racemates , after he had 

 accidentally observed that these can grow in them. He tried to 

 answer the question, as to what would be the behaviour of the two 

 components of the racemate under the influence of the living 

 organism. 



He found that the originally inactive solution became gradually 

 lae vogyratory ; the organism (Penicillium glaucum) had evidently 

 selected for its nutriment that form of the tartaric 0aW-molecule 

 which suited best its particular needs. Although this selective con- 

 sumption of one of the antipodes by living organisms has often been 

 found, it must, however, be recognised that the selective fermen- 

 tations as a general phenomenon, have not yet been studied 

 exhaustively in a sufficiently systematic way 1 ). In numerous cases 

 we do not know whether the culture used was of only one species, 

 nor to what species the organisms belonged in many cases. 

 Neither is there certainty as to whether the organism merely 

 decomposes one active component of the mixture more rapidly 

 than the other, or whether it leaves one of them entirely intact. 

 Most probably there is only a great difference of rate of velocity. 



It may be thought most remarkable, that such a relatively minute 

 difference between two molecules should be sufficient to cause such 

 a fundamental difference in the behaviour of a living organism, if 

 brought into contact with it. More recent experiments, however, have 



*) As an interesting contribution, however, see: W. Pfeffer, Jahrb. f. wiss. 

 Botanik, 28, 205, (1892). 



