180 



HEMOGLOBIN 



There are in addition the experiments of Ma^ela and Seli§kar(9), in 

 which the temperature coefficient of the equihbrium constant in 

 dilute solutions of haemoglobin was explored. Reference has already 

 been made to these experiments in Chapter v, in which their relation 

 to the problem of specificity is discussed. Here therefore it will only 

 be necessary to treat of them very shortly. The measurements of 

 oxygen content are of course spectroscopic, and in addition there are 

 individual differences between different animals in the same species, 

 both of which factors make the results when plotted appear some- 



Fig. 59. 



what rugged. A good example is that of the blood of the frog. 

 Fig. 59 shows results from the blood of five frogs. The haemoglobin 

 concentration was made in each case equivalent to one-fortieth 

 of that in normal human blood, i.e. to about a 0-4 per cent, solution. 

 It was buffered to pH =7-4 and the data are plotted as shown in 

 Fig. 59, the logarithm of the pressure at 50 per cent, saturation 

 forming the ordinate and the reciprocal of the absolute temperature 

 the abscissa. It is quite clear that the temperature coefficient for 

 frog's blood is less than for mammahan blood and it is only about 

 half that of human blood. 



Another method of demonstrating that temperature has a great 



