W. N. M. RAMSAY 



haemoglobin ', as it did in Kallner's experiments. The experimental 

 error of the latter author, however, seems to have been a little higher 

 than that of Van Slyke et al, 25 and indeed was of much the same order 

 as the amounts of ' inactive haemoglobin ' detected in the more 

 recent work. 



It seems almost beyond doubt that many normal blood specimens 

 do contain minute traces of ferrihaemoglobin. This, however, does 

 not show the tendency to disappear that one would expect from the 

 work of Gibson 4 , and the possibility does not yet seem to have been 

 excluded that it may be an artefact arising as a result of dilution or 

 lysis of the cells. It seems also quite certain that the greater part of 

 the so-called ' inactive haemoglobin ' detected by the gasometric 

 methods is not ferrihaemoglobin. 



In conclusion, it may not be amiss to point out that the work 

 reviewed in this paper bears directly on a physiological topic of no 

 small importance which was the subject of much pioneering research 

 by the late Sir Joseph Barcroft : the percentage saturation of the 

 arterial haemoglobin with oxygen, and the relation of this to the tension 

 of oxygen in arterial blood. Certain work suggested that arterial 

 oxygen tension was as much as 20-30 mm (for references, see article 

 by D. L. Drabkin in this book) lower than would be expected on 

 physical and chemical grounds, and Roughton, Darling and Root 11 

 seem to have been the first to point out that the presence of small 

 amounts of inactive haemoglobin in fresh blood, which disappeared 

 during the course of in vitro experimentation, would go far to account 

 for the discrepancy. 



Received August 1948 



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2 — Ibid 118(1935)560 



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227 (1930) 245 



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14 — Ibid. 40(1946)286 



15 Kallner, S. J. Physiol. 104 (1945) 6 



238 



