CHAPTER VIII 

 FERMENTATION 



91. Importance of Fermentation. — In Chapter VII 

 (paragraph 78) reference was made to enzymes, which 

 have the power of causing marked chemical changes in 

 other substances without being thereby permanently 

 transformed or used up themselves. The number of 

 different kinds of enzymes now known is very great, and 

 it is probable that further investigation will reveal still 

 others not now recognized. One of the most interesting 

 and illuminating results of their study is the revelation 

 of the fact that one or more kinds of ferments or enzymes 

 are produced by every living cell (plant or animal), and 

 that life itself involves, and is in large measure depend- 

 ent upon, a series of fermentations. This truth, which is 

 becoming more and more firmly established by scientific 

 research, was recognized as early as 1839 by Schwann, 

 one of the founders of the cell-theory.^ His famous 

 work, '' Microscopical Researches," contains the following 

 passage: 



"I have been unable to avoid mentioning fermentation, 

 because it is the most fully and exactly known operation 

 of cells, and represents, in the simplest fashion, the 

 process which is repeated by every cell of the living 

 body." In fact, a knowledge of enzymes and fermentation 

 is necessary in order to understand some of the most 



^Cf. p. 15. 



94 



