64 HEMOGLOBIN 



some little consideration must be given to their interpretation. It 

 will be noted that the figures are spread both above and below 401, 

 the average being usually rather below that figure. 



There were two schools of thought with regard to these figures 

 when they were published. Of these the first taught that the sources 

 of analytical error were so great as to make more accurate analysis 

 impossible, whilst the second, represented chiefly by the late Prof. 

 Christian Bohr(iO) of Copenhagen, frankly admitted that the want 

 of uniformity was so great as to render untenable the idea of haemo- 

 globin as a single substance. He explained the divergences which 

 we have noted as being due to a mixture of four substances which 

 he called a-, jS-, y-, and S-hsemoglobins, each with a different oxygen 

 capacity from the others. 



To the schools mentioned a third was added by Wolfgang Ostwald, 

 which taught that the combination of oxygen and haemoglobin was 

 not in the old-fashioned sense a chemical combination, but a mani- 

 festation of the physical phenomenon known as adsorption, and that 

 it therefore depended upon electric charges on the molecules of the 

 oxygen and haemoglobin. The amount and nature of the charges 

 present might be supposed to vary, and, in so doing, affect the amount 

 of oxygen with which a given quantity of iron would imite. 



Lastly there is the school of thought now just opening which 

 regards the haemoglobin molecule not as something static but rather 

 as a dynamic system and one which involves the presence of other 

 iron-containing bodies. To what extent is the proportion which they 

 bear to haemoglobin constant? 



Since Bohr's time, partly on account of the improvements in the 

 analytical methods both for oxygen and iron, and partly on account 

 of the increased importance of the subject, it became more and more 

 desirable that some reinvestigation, by direct methods, of the specific 

 oxygen capacity of haemoglobin, should take place. I mean by direct 

 methods those in which the oxygen was measured as such and the iron 

 as a salt of that metal, as opposed to indirect spectrophotometric 

 methods, which have given uniform and apparently excellent results 

 in the hands of Butterfield. This investigation was undertaken by 

 Peters* (11); for the purpose of estimating the oxygen he used the 

 differential method of blood-gas analysis, based upon the observation 

 of Haldane that oxygen is eliminated from haemoglobin quantitatively 

 by potassium ferricyanide(i2). 



* Now Professor of Biochemistry at Oxford. 



