CARBON MONOXIDE— REDUCED HEMOGLOBIN 149 



curves for oxyhsemoglobin at approximately the same COg-pressm-es 

 (5, 20, 40 and 80 mm.). The abscissa (on the top of the figm-e, 

 the oxygen pressure in millimetres) is of course widely different from 

 that for the CO-haemoglobin, and the scales are so arranged that 

 the point of 50 per cent, saturation on the 80 mm. curve coincides 

 for each series. That is to say, the oxygen pressures throughout for 

 the oxyhsemoglobin curves are 38: -156 or 245 times those of the 



10 2 30 4 50 60 70 80 90 



'005 '010 '015 

 CO Pressure 



•020 -025 -030 -035 



•040 ^045 -050 

 % Atm. 

 mm.Hq 



•05 -1 -15 -2 ^25 -3 -35 



Fig. 47. Equilibrium curves of Hb and CO at 0, 19, 41 and 79 mm. COg-pressure 

 respectively, x indicate curves for Hb and Og equilibrium drawn with reference 

 to abscissa indicated at the top of the figure. 



carbon monoxide for the CO -haemoglobin curves. The figure 245 

 we need not discuss here. We shall see later that it depends 

 upon the kind of animal, the temperature, etc. The point is that 

 there is a constant relation over two sets of curves, one for oxy- 

 hsemoglobin and the other for carboxyhsemoglobin, so that in a 

 specified case a number can be given which apphes to the whole 

 diagram. In the present case you can say that if a certain pressure of 



