THE BIOCHEMISTRY OF RESPIRATION 269 



higher animals the hydrolytic changes which form such a 

 marked feature in lower organisms have sunk largely into 

 abeyance. The oxidation mechanisms have developed so 

 enormously in the course of evolution and appear to have 

 become so efficient that it is unnecessary for them to depend 

 to any great extent on preceding hydrolyses. Just as hydrogen 

 peroxide, acting in vitro in the presence of a catalyst, can 

 oxidise fatty acids and other substances directly to C0 2 and 

 water, so may intracellular oxidases effect similar direct 

 oxidations within the cell. We have some experimental 

 evidence in support of these direct oxidation processes, for 

 Neuberg ' found that animal tissues could oxidise glucose to 

 glycuronic acid, and it seems probable that plants can oxidise 

 it to malic and tartaric acids. 2 



1 Neuberg, " Oppenheimer's Biochemie," Erganzungsband, p. 569, 191 3. 



2 Cf. Lesser, Ergeb. d. Physiol. 8, p. 796, 1909. 



