SECTION XVII. 

 THE ENZYMES AND ENZYME ACTIONS OF YEAST. 



CHAPTER LXIIL 

 ALCOHOL A SE. 



By DR. RUDOLF RAPP, 



Chief Pharmacist of the Munich Municipal Hospital. 



316. Historical Introduction. 



AFTER the vegetable nature of yeast had been demonstrated by 

 CAGNIARD-LATOUR (II.) and T. SCHWANN (I.), and the theory of its 

 fermentative action had been thereby diverted into new channels, 

 the succeeding decades witnessed the rise of a series of theories 

 which endeavoured to assign the fermentative property of yeast 

 to actions that were partly physical, partly chemical, and partly 

 physiological. The most important of these theories have been 

 already discussed in vol. i. (pp. 12-23). 



The fact that, until recently, Pasteur's theory on this subject 

 found the largest number of adherents was due to its being the 

 most intelligently developed and to the circumstance that the 

 systematic investigations of that authority first laid the founda- 

 tions of the chemistry of fermentation. Moreover, Pasteur based 

 his work on the labours of Schwann, whose disciple he professed 

 himself see DELBRUCK (VII.) so that he was not really the 

 founder of the new epoch. 



In the present paragraph we will deal chiefly with the theories 

 in which fermentation is ascribed to the action of enzymes, to 

 which class belong the hypotheses of M. Traube, J. Liebig and 

 Hoppe-Seyler. TRAUBE (I.) wrote : " Yeast acts as a chemical 

 ferment, which transmits the oxygen present in combination in 

 one chemical substance to another substance," that is, it is capable 

 of acting as a reducing agent on the one hand, and as an oxidising 

 agent on the other. This view was quickly shared by M. BER- 

 THELOT (V.) and was repeated by TRAUBE (II.) in 1874, after 

 BREFELD (XIII.) on the basis of a somewhat doubtful method of 

 experiment had come to the not very expressive conclusion that 



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