The dissociation curve of haemoglobin 



23 



another theory also advanced to explain the same curve demands 

 consideration. It is the theory that oxygen is united to the haemo- 

 globin, not chemically in the ordinary sense of the word but by the 

 physical process known as adsorption, that is to say that small masses 

 of haemoglobin, each composed of a number of molecules, exist in or 



10 



20 



30 



40 



50 



60 



70 



80 



100 



FIG. 12. Ordinates = percentage saturation of haemoglobin with oxygen. Abscissae = 

 tension of oxygen in mm. of mercury. Curve I = rectangular hyperbola. .XT=800. 

 Curve 11 = Bohr's dissociation curve of haemoglobin. 



O Points determined from dialysed solution. 

 Q Points determined from undialysed solution. 



out of the solution and that the surface charges on them attract mole- 

 cules of oxygen which adhere to the surface of the haemoglobin. The 

 phenomena of surface effects are destined to play so great a part in 

 the future of physiology that this theory, which is due to Wolfgang 

 Ostwald (5) , is well worth the consideration of those interested in the 



