CHEMICAL FERMENTS. 575 



Such ferments play an important role in physiological 

 processes, especially in the nutrition of the body. 

 Stated generally, they have the power of so transforming 

 materials which, as such, cannot enter an organism, nor 

 perform any function in it, that they become soluble, 

 diffusible, and capable of being utilised as nutrient 

 substances. Insoluble albumen is converted into peptone ; Importance 

 starch and cellulose into soluble dextrose ; fat is broken cesses^rf 10 " 

 up; cane-sugar, which cannot be decomposed in proto- nutrition - 

 plasm, is converted into glucose, which is readily acted 

 on. The most highly organised animals require these 

 ferments just as much as the most lowly organisms; the 

 former prepare them in special glandular organs, but 

 even in the lower fungi, in which no organs can be 

 distinguished, ferments are nevertheless a very common 

 product of tissue change, and one necessary for nutri- 

 tion. 



As regards the mode of action of these ferments, the 

 most striking point is that a relatively small quantity 

 suffices to transform a large quantity of the body which 

 is being broken up ; the whole chemical action, therefore, 

 seems to run its course without the ferment itself playing 

 an active part or becoming altered. This circumstance 

 led to the use of the term " ferment," as applied to the 

 chemical bodies of which we are speaking, and to the 

 inclusion of the processes set up by them in the same 

 class with the fermentative and putrefactive processes. 

 Indeed, many investigators look on it as probable that 

 all the fermentative processes may be referred to such 

 chemical ferments, and believe that it is only by such a 

 view that it is possible to understand aright the processes 

 of fermentation. 



Nevertheless the investigations which have been made 

 as yet, compel us to take the view that the true fer- 

 mentations, and the action of isolated chemical ferments, 

 differ so much from each other that they must both be 

 treated separately. As a rule, however, the chemical 

 ferments play a part, and, in fact, set agoing many 

 complex fermentative and putrefactive changes; and 

 they play an important rdle in the nourishment of many 



