OXYGEN FIXATION 591 



Sufficient has been said to indicate that very complex 

 conditions prevail in connection with the fixation of oxygen 

 by haemoglobin and that it is scarcely possible to express 

 these by a simple formula. For a long time the Hiifner 



formula, c = K q Po A * > was popular (Co representing the 



amount of oxyhaemoglobin, Cr that of reduced haemoglobin, 

 K a constant, p the oxygen tension at the surface of the solu- 

 tion, and a t the absorption coefficient at temperature, t). 

 Later, however, objections from various sources have been 

 raised against this formula. Thus Bohr assumes in the first 

 place that while the combination of iron-free globin with 

 iron-containing haemochromogen may be hydrolytically 



H G F 



dissociated (Haemoglobin ^ Globin + Haemochromogen) ; 

 on the other hand there may be an equilibrium, F j;F + 

 2O 2 , F representing the iron-containing haemoglobin frac- 

 tion combined with oxygen. From this assumption Bohr 

 arrives at a rather complicated formula of dissociation. 28 V. 

 Henri believes that we may more satisfactorily harmonize 

 theory and practice by assuming that two molecules of hae- 

 moglobin unite with one molecule of 2 . 29 Manchot 30 is of 

 the opinion that haemoglobin is capable of combining oxygen 

 and other gases in the same way that sulphate of iron com- 

 bines nitrous oxide or chlorate of copper fixes carbon mon- 

 oxide, and holds that the laws of equivalence and mass action 

 are sufficient to explain the complex phenomena. Barcroft 

 and Hill 31 regard it as almost beyond doubt that dissocia- 

 tion of oxyhaemoglobin takes place in accord with the equa- 

 tion, H b + 2 ,Z^H b 2 , and follows the law of mass action ; 

 has a high temperature coefficient and increases four-fold 



28 Cf. A. Lowy, Handb. d. Biochem., 4', 53-54, 1908; B. v. Reinbold, XVI 

 internat. Mediz. Kongress, Budapesth, 1909, S. A. 



29 V. Henri, C. R. Soc. de Biol., 56, 339, 1904. 



80 W. Manchot (Chem. Instit., Wiirzburg), Ann. d. Chem., 870, 241, 1910; 

 372, 179, 1910. 



81 J. Barcroft and A. V. Hill (Physiol. Lab., Cambridge), Jour, of Physiol., 

 89, 411, 1910. 



