THE PURPOSE OF FERMENTATION 39 
The yeast ferments sugar, and bacteria putrefy proteids for uses 
of their own. Incidentally it may result that the natural proc- 
esses of life phenomena are benefited thereby; but primarily all 
of the enzymes secreted and all of the fermentations produced are 
for the benefit of the organisms secreting them. If a bacterium or 
a mold secretes an enzyme into a lot of milk which causes its diges- 
tion, its purpose is to digest the milk for its own use and not for 
any incidental results that may accrue to the cheese-maker. 
