MATTER AND ENERGY 75 



the protoplasm of the cell, or possibly in the 

 substances stored in the cell. They may thus 

 carry on metabolic changes, during the life of 

 the cell, and they may even cause destruction 

 of the cell after death, by a kind of auto- 

 digestion, or autolysis. 



34. Most enzymes are hydrolytic, that is 

 to say, we may represent their action by the 

 addition of water to the fermentable matter 

 and then a decomposition. Thus cane sugar 

 plus water plus the enzyme, is changed into 

 dextrose and levulose, two other varieties of 

 sugar. But other enzymes are believed to 

 carry oxygen to the tissues. These have 

 probably to do with respiratory processes. 

 They are termed oxidases. 



35. Enzymes may be readily classified 

 thus : 



(1) Amylolytic Change polysaccharides 

 such as starch into sugar. Example : Ptyalin 

 of saliva and the diastase of plants. 



(2) Invertins Change disaccharides into 

 mono-saccharides. Ex. : Invertase of intestinal 

 juice, which changes cane sugar into dextrose 

 and levulose. 



