46 



HEMOGLOBIN 



For sheep's hsemoglobin in dilute solution, Hartridge and Roughton (12) 

 give the figure 3-8 as representing the temperature coefficient. This, 

 though somewhat less than that of human haemoglobin, is still very 

 high. 



A comparison of the effects of temperature on the haemoglobins of 

 several forms of life, widely scattered over the animal kingdom, is 

 shown in Fig. 10. The units in which this figure is plotted demand 

 a word of explanation. Take for instance the three points given for 

 human haemoglobin. They are derived directly from the data given 

 above. The theory need not be discussed at this stage. The pressures 

 f or haK-saturation are respectively 0-3 mm., 1-5 mm. and 7-5 mm., 



Fig. 10. (See text.) 



or 30, 150 and 750 hundredths of a millimetre. The logarithms of 

 these figures are plotted vertically. The horizontal reading is not the 

 absolute temperature but its reciprocal. Thus 25° centigrade is 298° 

 absolute, its reciprocal being -00336. The effect of temperature then is 

 represented by the slope of the line corresponding to any particular 

 animal. The difference between man and the frog both in the affinity 

 for oxygen and in the effect of temperature on that affinity is easily 

 seen. 



In only a very few cases have the curves expressing the equilibrium 

 between reduced haemoglobin, carboxyhaemoglobin and carbon mon- 

 oxide been determined, but the following data are forthcoming (8): 



