114 THE THEORY OF IONS 



known to be catalysers, so the important role of 

 oxygen-carrying by the oxidases has been ascribed 

 to these salts. 



In animal organisms, oxidation has been looked 

 upon as a combustion of material. This comparison 

 may still be considered to hold good. In the com- 

 bustion of devitalised organic products, such as 

 wood, coal or oil, there is first a decomposition into 

 other substances before the phenomenon of light is 

 produced. In the living organism, chemical energy 

 is transformed into heat and work by various oxi- 

 dations, whereby there is a cleavage of complex 

 substances into simpler and more stable compounds. 

 Such a decomposition results from the preliminary 

 dissociation of water into H and OH ions, which 

 react upon the substance to be decomposed ; it is 

 called a hydrolytic cleavage, e.g. 



Tristearin Glycerine Stearic acid 



C 3 H 6 (C 18 H 36 2 ) 3 + 3H 2 = C 3 H 5 (OH) 3 + 3C 18 H 36 O 2 . 



Such cleavages can be produced outside the body 

 by means of acids and alkalies. But the animal 

 organism has a better way of producing the cleavage, 

 and that is by means of the enzymes ; such as the 

 proteolytic, amylolytic and lipolytic enzymes of the 

 alimentary canal. 



The action of the enzymes seems to depend upon 

 the stereometric construction of the molecules acted 

 upon. Each acts upon a special kind of substance or 

 is monotropic ; thus, the enzymes of yeast act only 

 upon a-glucosides, while emulsin will only act upon 

 6-glucosides. But the manner of their action is still 

 unknown. Certain work done by Ikeda, Bredig and 



