1184 



PHYSIOLOGY 



pressure of the carbon dioxide. At lower pressures of oxygen, how- 

 ever, the pressure of carbon dioxide makes a considerable difference. 



100 

 90 

 SO 

 70 

 60 

 SO 

 +0 

 30 

 20 

 10 



Ul 



L 



L 



7 



7 



L 



10. SO 30 W 50 60 70 80 3d tOO HO J20 130 fW 450 



FIG. 495. Effect of varying tensions of CO., on the dissociation curve of oxyhaemo- 

 globin. The lowest curve is the dissociation at a C0 2 tension of 420 mm. Hg. 

 from observations by Barcroft. (BOHR.) 



SO 



. 



21 



20 30 <0 50 60 70 SO SO 100 



FIG. 496. Dissociation curves of sheep's blood. 



1, normal blood; 2, blood containing 0'04 per cent, added lactic acid ; 

 3, blood containing O08 per cent, added lactic acid. 



Thus at an oxygen pressure of 20 mm. Hg. the amount of oxyhaemo- 

 globin formed is 67-5 per cent, at a carbon dioxide pressure of 5 mm., 

 whereas at a pressure of carbon dioxide of 40 mm the amount of oxy- 



