196 



HEMOGLOBIN 



protein, CO-haemochromogen has a hyperbolic dissociation curve. 

 It would seem therefore that the double inflection was in some way a 

 function of the protein, but how ? Well, the reader may read Chapter xn 

 once more and may see whether he there finds a really satisfactory 

 answer to the question. If not he has food enough for thought. Some- 

 times I have wondered whether the double inflection depended upon 

 some question of solubility, but no simple combination of a hyperbola 

 with a dissociation curve, such as shown in Fig. 63, will meet the case. 



100 

 90 

 80 

 70 

 60 

 50 

 40 



30 



20 



10 



10 20 30 40 50 60 

 Oxygen pressure mm. 



70 80 90 100 



Fia. 63, A. Hyperbola corresponding to 96 per cent, saturation and 100 mm. pressure. 



B. Hyperbola corresponding to 40 per cent, saturation and 66-6 mm. pressiire, 



C. Dissociation curve of blood (Christiansen, Douglas and Haldane), 



Not only is the dissociation curve of blood wonderfully efficient 

 in view of the considerations which have just been stated, but almost 

 as interesting is its reserve capacity. Every form of life must 

 face emergencies and the one which survives them is that best 

 calculated to meet the strain. Now here the necessary form of adjust- 

 ment, or one factor in it, is that when the tissue requires a greater 

 supply of oxygen the blood should be capable of imparting it with 



