170 HEMOGLOBIN 



Assuming, for the sake of argument, the dissociation curve of 

 Barcroft and Roberts for dialysed haemoglobin, 8-1 virtual mm. of 

 oxygen would correspond to 61 per cent, of gas-combined haemo- 

 globin and 49 per cent, of reduced haemoglobin. Of the 51 per cent, 

 of gas-combined haemoglobin how much is oxy- and how much is 

 carboxyhaemoglobin ? 



[CO] --01-^^^' 

 from Fig. 53 it appears that 



PTTi /^An will therefore be ^;- . 

 [HbCO] 1 



Therefore out of 2-6 parts of haemoglobin 1-6 will be HbOg and 1-0 will 

 be HbCO, out of 51 parts 31-4 will be HbOa and 19-6 will be HbCO, 

 so that the whole haemoglobin would be divided as follows (Fig. 54) : 



Reduced haemoglobin ... 49 parts 

 Oxy haemoglobin ... 31-4 „ 



CO-haemoglobin ... 19-6 „ 



Total haemoglobin 100 „ 



Or to take another example, suppose haemoglobin is exposed to a 

 mixture of 20 mm, Og and -032 mm. CO. The CO corresponds to 

 •032 X 310 = 10 virtual mm. of oxygen, making the equivalent of 

 30 oxygen mm. That on the curve would correspond to 20 per cent, 

 of reduced haemoglobin and 80 per cent, of a mixture of oxy- and 

 carboxyhaemoglobin. The proportion of these last to one another is 

 found in Fig. 53 which really amoimts to this : 

 [HbOg] _ Pressure of Og 



[HbCO] Pressure of CO expressed in virtual mm. of Og" 



Therefore the 



[HbOg] _ 20 

 [HbCO] ~ 10' 



so that of the whole haemoglobin : 



Reduced haemoglobin 20 per cent. 

 HbOa = |§ X 80 53 



HbCO = 1^ X 80 27 



Total haemoglobin 100 „ 

 It will be observed that in both the cases I have given there is less, 

 both of oxy- and of carboxyhaemoglobin, than if reduced haemoglobin 



