66 SCIENCE PROGRESS 



But reductase is not merely a deoxidiser. Although in Nature 

 it is concerned only with the reduction of oxyhemoglobin, yet 

 it is a true reducer : it can reduce substances as stable as soluble 

 Prussian blue, alizarine blue, methylene blue, and indigo blue; 

 it can reduce nitrates to nitrites and ferric chloride to ferrous 

 chloride. Let us, therefore, in the light of recent work not 

 hesitate to bring tissue respiration under the category of 

 fermentation. Its oxidative side is now generally admitted to be 

 endo-enzymic ; let us complete the conception and regard its 

 reducing or inspiratory aspect as also endo-enzymic. 



