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. 1 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 
