204 BIOLOGY OF SPECIALIZED GROUPS 



cussion to mean the breaking up of complex carbohydrate 

 compounds by the action of the enzymes of microorganisms. 



Furthermore, the terms " ferment " and " enzyme " are 

 often used in different senses. Fermentation, according to 

 many writers, is applied to a direct metabolic function of the 

 viable protoplasm of cells which serves them as a source of 

 energy, while enzyme action is not dependent upon living 

 protoplasm of cells and does not furnish any energy to the 

 cells. The above distinctions raise many objections. 



Organized and Unorganized Ferments. Many writers 

 make a division of the agents of fermentation into organized 

 ferments and unorganized ferments or enzymes. It is stated 

 that organized ferments are living cells, such as bacteria, 

 yeasts, molds, etc., and are only able to produce chemical 

 changes so long as the cells are alive. Enzymes are con- 

 sidered to be chemical substances, the secreted products of 

 cells, and capable of producing marked chemical reactions 

 in organic compounds in the absence of the cells producing 

 them (pepsin, trypsin, ptyalin, etc.). It is claimed, however, 

 that the organized ferment and the enzyme may act in a simi- 

 lar manner in many cases. Fischer says that in both cases 

 the chemical changes produced are specific and are performed 

 without the loss of energy, and that the ferment substances 

 themselves do not enter into the reaction. Fischer also 

 states that enzymes exercise a hydrating influence which 

 causes the substances that are attacked to take up water and 

 form substances of an entirely different chemical constitution. 



