ON THE USE OF SOLUBLE PRUSSIAN 

 BLUE IN INVESTIGATING THE RE- 

 DUCING POWER OF LIVING ANIMAL 

 TISSUES 



By DAVID FRASER HARRIS, M.D., B.Sc. (Lond.) 



Lecturer on Physiology and Histology in the University of St. Andrews 



The reducing power which living tissues possess is a property 

 of the utmost importance from the biochemical standpoint. 

 All animal bioplasm has in greater or less degree an oxygen 

 avidity 1 in virtue of which it abstracts oxygen from some 

 substance holding that element in a dissociable union. In the 

 higher animals it is oxyhaemoglobin that is thus partially 

 reduced : this is a case of direct deoxidation : on its efficiency 

 depends the continued existence of the bioplasm. 



Living tissue can, however, act as a chemical reducer under 

 conditions which do not admit of deoxidation. To this aspect 

 of the vital metabolism I directed my attention in 1896, 2 and 

 found that the reducing power of bioplasm can be rather strik- 

 ingly shown by the use of the soluble Prussian blue and gelatine 

 " mass " well known to histologists for injecting blood-vessels. 

 Organs injected with abundance of this blue material frequently 

 appear "failures" from the histological point of view, in that 

 their smaller vessels seem so pale or so devoid of colour as not 

 to be capable of being demonstrated. This change of colour 

 from blue to pale green or even to a " white " (leuco) condition, 

 I believe is due to the intra vitani reduction of the potassio- 

 ferric-ferrocyanide, 



(CN) 3 - K 



Fe"/ \ ¥e '" 



\cn/ 



1 Paul Ehrlich, Das Sauerstoff-Bediirf?iiss des Orga7iismits, Berlin, 1885. 



2 D. F. Harris, Proc. Roy. Soc. Edin., Session 1896-7, vol. xxi. 



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