THE ROLE OF REDUCTASE IN TISSUE 



RESPIRATION 



EY 



DAVID FRASER HARRIS, M.D., D.Sc, F.R.S.E., 

 Professor o Physiology and Histology in DalhoMsie University, Halifax, N.S. 



AND 



HENRY JERMAIN MAUDE CREIGHTON, M.A., M.Sc, D.Sc, 

 Assistant Professor o f Chemistry in Swarthmore College, Swarthmore, Pa., U.S.A. 



It has been known for a long time that living tissues possess 

 both reducing and oxidising powers. In 1883 Hoppe-Seyler 

 drew attention to the strong reducing processes in living tissues; 

 and Professor Theobald Smith has recently used liver juice as 

 the best agent with which to close the open end of a tube where 

 bacteria were to grow under anaerobic conditions. Ever since 

 the time of Lavoisier it has been certainly known that the carbon 

 dioxide and water eliminated from the animal body have been 

 produced by the oxidation of carbon and hydrogen within it. 

 It was originally held that this "carbonaceous" oxidation took 

 place in the blood itself; but the undoubted production of carbon 

 dioxide by a frog whose blood had been replaced by salt 

 solution showed that at least that gas must have originated in 

 the tissues and not in the blood. Oxidation and reduction 

 evidently go on side by side within the living tissues ; oxygen 

 they must have, and they soon die if it is withheld. The source 

 of this oxygen is of course the respiratory pigment, oxyhemo- 

 globin, whose loosely held oxygen is removed by the tissues, 

 which are, therefore, said to have oxygen-avidity (Sauerstoff- 

 Bediirfniss) or reducing power. This continual oxidation of 

 materials within the tissues and the reduction of the oxyhemo- 

 globin in the circumambient blood is conveniently called tissue 

 respiration. Within the last few years attempts have been made 

 to gain a clearer insight into both the processes of tissue oxidation 

 and tissue reduction, with the result that both are now thought 

 of as carried out by intracellular ferments. Many workers on 

 the Continent of Europe and in England have studied the action 



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