292 



RESPIRATION 



Combining Power of Hemoglobin with Oxygen. One hundred 

 cubic centimeters of blood contain about 14 grams of hemoglobin, page 133. 

 Each gram of hemoglobin, when fully saturated with oxygen, according to 

 Hiifner's earlier determination, conbines with i .56 c.c. of oxygen. By later 

 work he gets the determination of i . 34 c.c. for hemoglobin of ox blood. 



100 

 90 



80 

 70 

 GO 



50 



40 



30 



'20 



10 



10 



20 



30 



40 



50 



GO 



90 100 



FIG. 238. Dissociation curves of oxyhemoglobin. The figures along the ordinates 

 represent percentages of saturation of hemoglobin by oxygen. The figures along the 

 abscissse represent mm. of oxygen pressure in mercury. 



I. Bohr's dissociation curve of oxyhemoglobin dissolved in water. 



II. Dissociation curve of oxyhemoglobin dissolved in Ringer's Solution. (After 

 Bancroft and Camis.) 



This last figure indicates that the combining power of the hemoglobin is 

 dependent upon the iron in the molecules, in which one atom of iron combines 

 with one atom of oxygen. A number of investigators have examined the 

 conditions under which hemoglobin combines with oxygen Hiifner, Bohr, 

 Lowy, and Bancroft and Camis. Hiifner, working with purified hemo- 

 globin in watery solution, found that when the oxygen tension in the air in 

 contact with the hemoglobin was increased above zero by graded stages, 



