100 



HEMOGLOBIN 



this new technique it is possible to determine the equilibrium curve 

 of the system, Og-haemoglobin, reduced haemoglobin and oxygen, on 

 solutions of a quite dilute order — such for instance as might contain 

 haemoglobin in the concentration of one in one thousand. 



Roughton (see Fig. 28) determined some points on this curve. 

 The method is not very reliable except at such points on the curve 

 as involve a considerable quantity both of oxy- and of reduced 

 haemoglobin in the mixture — say between the limits of 30 per cent. 

 OgHb with 70 per cent. Hb and 70 per cent. OgHb with 30 per cent. 



'4>O^Hh 



2 4-6 



O2 Pressure, in Mm 

 Fig. 28. 



8 



Hb. Over this region of the curve it is clear that Hartridge and 

 Roughton's(9) points are as nearly as may be on a rectangular hyper- 

 bola. But also it is clear that a curve which was far removed from 

 being hyperbolic could be drawn through the points without greater 

 error than the hyperbola. Moreover, the really crucial points are not 

 those in the middle of the curve. 



It was of course impossible to leave a matter so important as the 

 fundamental character of the oxygen dissociation curve in so un- 

 satisfactory a state. Dr Selig Hecht and I(iO) therefore evolved a 

 very simple technique for the purpose of studying the dissociation 



