10 INTRODUCTION. 



from the lactic-acid bacilli and beer vinegar bacteria, it is possible to 

 separate the specific fermentative principle of these organisms from the 

 living organism and to bring about changes with the dead organism 

 (E. BUCHNER, and MEISENHEIMER and GAUNT, HERZOG 1 ). The ques- 

 tion whether there exist ferment processes which, in PASTEUR'S sense, 

 are the result of the biological phenomena connected with the metab- 

 olism of the micro-organism and which we can directly identify with the 

 life processes, is very difficult to answer; hence for the present we have 

 no foundation for a sharp differentiation between the organized ferments 

 and enzymes. The metabolic processes of the living organisms which 

 we recognize as fermentation phenomena must as a rule be ascribed to 

 enzymes acting within the cell. If such processes are closely connected 

 with the life of the cell, then this is explained in part by the fact that 

 this special enzyme is produced only by living cells and in part by the 

 fact that it cannot be separated from the living cells or that it is readily 

 destroyed on the death of the cell. 



All enzymes and ferments, both names having now the same signifi- 

 cance, are considered as organic substances formed in the cells but whose 

 chemical nature has not been determined for the present. 



We have no characteristic reaction for all enzymes or ferments 

 in general, but each enzyme is characterized by its specific action and 

 by the conditions under which it operates. Of special importance is, 

 first, the fact that the enzymes do not form permanent chemical com- 

 binations in definite proportions by weight with the bodies upon which 

 they act, or their decomposition products; and, secondly, that an insig- 

 nificantly small amount of the enzyme can decompose a relatively enormous 

 amount of substance. For instance, 1 part of invertin can invert 100,000 

 parts of cane-sugar (O'SuLLiVAN and THOMPSON 2 ), and 1 part of chy- 

 mosin can in a short time decompose more than 400,000 parts of casein 

 (HAMMARSTEN 3 ) . This does not exclude the possibility of a primary, 

 but temporary, combination of the .enzymes with the substances acted 

 U pon a process which is highly probable from the numerous observa- 

 tions which will be discussed in Chapter II. 



The specific action of the enzymes is of special importance, as one 

 and the same enzyme acts only upon one substance or a definite group 

 of substances. Their action seems to be entirely dependent upon the 

 stereometric construction of the substance acted upon, which will be 

 discussed in Chapter II. 



The relationship of the enzymes to the inorganic catalysts is also of 



1 E. Buchner and J. Meisenheimer, Ber. d. d. chem. Gesellsch., 36; and Annal. 

 d. Chem. u. Pharm., 349; with Gaunt, ibid., 349; Herzog, Zeitschr. f. physiol. Chem., 37. 



2 O'Sullivan and Thompson, Journ. of Chem. Soc., 57. 



3 See Maly's Jahresbericht, 7. 



