108 



HEMOGLOBIN 



solutions (say of the order of one part of haemoglobin to 1000 of water) 

 take up or give out oxygen. The work of Adair (6), however, shows that 

 the osmotic pressure of the haemoglobin does depend upon the saline 

 content of the solution in which it is dissolved ; above a certain saline 



Fig. 32. Ordinate = percentage saturation of haemoglobin. Abscissa = tension of 

 oxygen in mm. of mercury. 



I. Dissociation curve of haemoglobin dissolved in water. 



II. „ „ .. "7 per cent. NaCl. 



III. „ „ „ 9 per cent. KCl. 

 Rectangle surrounding point = magnitude of experimental error. Temperature 



37-38° C. 



content the osmotic pressure is stable over a large range. Stabili- 

 sation of the osmotic pressure likely enough means stabilisation of the 

 degree of inflection of the oxygen dissociation curve. 



The effect of hydrogen-ion concentration. It will clear the ground 

 to commence by saying that, so far as is known, the effect of carbonic 

 acid on haemoglobin is not specific but is due to alteration of the 



