74 A TEXTBOOK OF PHYSIOLOGY 



oxygen free and then transfer it to the body to be oxidized. Ail 

 example of oxidizing action occurring in the body is the following : 



C 5 H 4 N 4 + O = C 5 H 4 N 4 O 2 + O = C 5 H 4 N 4 O 3 



Hypoxanthin Xanthin Uric acid 



The oxidases give a blue colour with tincture of guaiacuin alone, the 

 peroxidases with tincture of guaiacum in the presence of peroxides. 



According to recent investigations, it is claimed that oxidases 

 are in reality a mixture of oxygenases, bodies containing iron and 

 manganese, and peroxidases. The oxygenase in the process of 

 oxidation is believed to take up molecular oxygen and become 

 converted into peroxide. This peroxide is then activated by the 

 peroxidases, and has a great oxidizing power. 



It is possible that certain of the reductions taking place in the 

 body may be ascribed to the presence of enzymes known as " re- 

 ductases." More light is required on this subject; some of the 

 eductions in the body are apparently not of an enzymic nature. 





