168 HEMOGLOBIN 



however, altered completely the current conceptions of the dissociation of oxy- 

 haemoglobin and this fact alone rendered a further investigation of Haldane and 

 Lorrain Smith's conclusions very desirable.... And Dr Krogh(5) had also kindly 

 informed us by letter that he had obtained results different from those of Haldane 

 and Lorrain Smith when he used the blood of a different animal. 



The necessity of undertaking this work was as evident in Cambridge 

 as in Oxford and therefore it happened that quite independently the 

 equihbrium between CO, Og and haemoglobin was investigated both 

 by the authors just quoted and by Hartridge(3). Both published 

 their results in 1912. 



These researches agreed that alterations of hydrogen-ion concentra- 

 tion had no influence upon the relative affinities of O2 and CO for 

 haemoglobin. The following table, given by Hartridge, aptly illustrates 

 the point : 



CO-hsemoglobin in tubes containing various concentrations of CO in air 

 A B C D E 



In each column the gas mixture is the same for the three samples. 



The Oxford observers, who determined the CO-Og-Hb dissociation 

 curve with haemoglobin to which CO2 and NagCOg had been added, 

 similarly found that neither the CO2 nor the Na^COg had any ap- 

 preciable influence on the result. 



Salts also appear to have no effect on the equihbrium. With 

 temperature it is otherwise. Temperature has a definite effect on the 

 reaction, though this effect is trifling as compared with the effect 

 of temperature on the affinity of haemoglobin for either gas separately. 

 Thus, according to the determinations of Haldane and his collabo- 

 rators, the equihbrium constant of human haemoglobin at 37° C. 

 is 250, at 15° C. it is 400 — an alteration of 10-20 per cent, for a 

 change of temperature of 10°; it will be remembered that the 

 equilibrium constant of the reaction 



Hb + O2 :^ HbO 



has a temperature coefficient of about 400 per cent, over the same 

 range of temperature. 



Whilst the factors which influence the reaction of haemoglobin with 

 oxygen have Uttle influence on the equihbrium of haemoglobin with 

 the oxygen and carbon monoxide simultaneously, there is another 



