EFFECT OF TEMPERATURE ON HEMOGLOBIN 185 



where T^ and T^ are the initial and final absolute temperatures, 

 in this case 299° and 311° C, and p^ and ^2 ^^e the pressures at 

 which the haemoglobin is 64 per cent, saturated at those tempera- 

 tures. 



In the nature of things, as has already been said, Q need not be 

 the same for all saturations, but so far as the present experimental 

 evidence goes Q is the same for all satiu-ations on the same sample of 

 haemoglobin because the ratio of ^2 to p^ seems to be the same right 

 up the curve. Therefore, in theory, the same amount of heat should 

 be given out per 32 grams of oxygen absorbed, whether that 

 oxygen is employed partially or completely saturating the haemo- 

 globin. In actual practice some observers of the heat developed have 

 adopted the method of partial and others complete oxidation; the 

 answer should come out the same and therefore it is open to the 

 experimenter to use whichever method offers fewest opportunities of 

 experimental error, but remembering that the vahdity of what he 

 is doing depends upon the constancy of the ratio of ^2/Pi ^^^ ^^y 

 given saturation at two different temperatures. 



The next point which perhaps may be taken up is the shape of 

 the curves. Clearly different samples of haemoglobin give curves of 

 different shapes : one may give a nearly hyperboHc curve, another a 

 curve which is considerably inflected. An example may be found 

 in my own work pubHshed with Hill. On two occasions we subjected 

 a haemoglobin solution to a given pressure of oxygen at different 

 temperatures, noted the saturations, assumed the hyperboKc nature 

 of the curve and then made a calculation which in essence amounted 

 to finding the pressures at which the haemoglobin was 50 per 

 cent, saturated at the various temperatures (or indeed saturated 

 to any other given point). Where do those calculations stand if the 

 curve is not a hyperbola ? As a matter of fact two of the temperatures 

 in question are the same as those used by King and myself, two others 

 are so close that a comparison can easily be made. Thus : 



