73 6 SCIENCE PROGRESS 



To judge of the possession of reducing power one must 

 observe the particular organ from the earliest moment of 

 perfusion, so that the organ, if in situ, must not be allowed to 

 be covered over by tissues which in its normal position hide 

 it from view. 



I am not prepared to give a table of the degrees of energy 

 of reducing power possessed by the various organs, but liver 

 and kidney stand high in the scale of possession of reducing 

 power ; the skeletal muscles and cortex cerebri would come 

 next in order, and then the glands. Hitherto I have studied 

 liver and kidney the most carefully by the Prussian blue method, 

 but I hope to investigate by this method the reducing power 

 of muscle, pulmonary tissue, spleen, and heart. 



The living tissues and organs must be regarded as reducing 

 agents in virtue of the same property by the exercise of which 

 they are deoxidising agents during their normal life in situ. 

 By the continued deoxidation of oxyhemoglobin they obtain 

 the oxygen necessary for their existence, but in the absence of 

 oxygen in such a loose chemical union as in oxyhemoglobin, 

 they can either deoxidise compounds in which the element is 

 much more firmly bound than in Hb0 2 — e.g. alizarine blue, 

 silver nitrate, osmium tetroxide ; or they can reduce such a 

 compound as methylene blue (which has no oxygen) to its 

 pale green chromogen, or, as in the case before us, a salt of 

 iron in trivalent form to one of iron in divalent. Viewed from 

 the physical standpoint, this last is a degradation of energy in 

 that the electrical charge on the ferri-ion is reduced to that on 

 the ferro-ion through the agency of the bioplasm. 



The continued existence of living bioplasm is ensured by 

 that avidity for oxygen which the living substance possesses ; the 

 taking of the gas into chemical union with itself constitutes 

 the inspiratory phase of tissue or internal respiration ; but if 

 oxygen, free or in loose union, be not available, the bioplasm 

 can, in virtue of this same oxygen-craving property, reduce 

 from "higher" to "lower" conditions certain substances which 

 contain no oxygen. 



It is this power of reduction as distinguished from the power 

 of deoxidation possessed by protoplasm which my experiments 

 demonstrate in regard to a soluble ferric salt ; undoubtedly both 

 phenomena are expressions of the same chemical activity on 

 the part of animal bioplasm. 



