THE SPECIFICITY OF HEMOGLOBIN 



49 



globin is shifted by exposure to CO, the greater the value of K in 

 the above equation (7). This is the more remarkable because no rela- 

 tion is known to exist between the absolute positions of the a-band 

 of oxyhsemoglobin and the affinity of haemoglobin either for oxygen 

 or for carbon monoxide. 



The somewhat mysterious relation between the shifting of the 

 «-band of oxyhsemoglobin towards the blue by saturation with CO, and 



48 49 50 51 52 53 54 55 56 57 58 59 60 61 

 Fig. 12. Ordinate = log K (see text); abscissa = span in Angstrom units. 



the affinity for CO relative to that for oxygen, is shown in Fig. 11, 

 in which the "span" is plotted against the value of K. The points 

 all have a large experimental error ; but the curve bears so logarithmic 

 a character that it seems worth re-plotting it as one in which the 

 "span" is plotted against the logarithm of K. The result is shown 

 in Fig. 12; the outer lines represent the expferimental error. No 

 great stress must be laid on the straightness of the central line. It is 

 very short and over so short a range portions of many shallow curves 



