94 



HEMOGLOBIN 



where f is the oxygen pressure to which the solution is subjected 

 and a the coefficient of solubility, therefore 



and replacing all the constants by one constant K, 



If the concentrations of oxy- and reduced haemoglobin are regarded 

 as percentages of the total concentration of haemoglobin, then 



K.p.Cr= 100- Cr, 

 Cr 100 



/ 1\^ 100 



Fig. 23. Rectangular hyperbola. The products of x and y, such as 

 ^i2/i» ^2y2» for *!" points are equal. 



If we write y for Cr and x for (p + ^], we obtain the relation- 

 ship a;y = a constant, namely „ . If we now construct a curve 



plotting y vertically and x horizontally, and observing the condition 

 that for any point the product of x and y must be constant, we obtain 

 a curve known as a rectangular hyperbola. 



This curve does not at first sight relate the concentration of 

 reduced haemoglobin {Cr^ to the pressure p, but to something else, 



