400 



THE RESPIRATION 



certain that the hemoglobin is acting in -the presence of the proper pro- 

 portion of salts, we shall find, as curve A shows, that at room temperature 

 the rate of oxidation is very much greater than the rate of reduction. 

 on 30 40 so 6Q TO go so TOO Oxidation 



17-5 C. no C0 9 



Reduction 



Oxidation 



37-5 C. no C0 2 



Reduction 



Fig. 141. Curves showing relative rates of oxidation and reduction of blood as influenced by 

 temperature and tension of CO 2 . 

 Ordinates Percentage saturation. 

 Abscissae. Time in minutes. 

 Reducing gas, hydrogen. 

 Oxidizing gas, oxygen. 



A, temperature 17.5 C., with no CO 2 . 



B, temperature 37.5 C., with no CO 2 . 



C, temperature 37.5 C., but the O 2 and H contained 40 mm. Hg pressure of CO 2 . (From 

 Joseph Barcroft.) 



If now we repeat the observation at a temperature of 37 C., the two 

 curves come more nearly to correspond, but still the rate of reduction is 

 slower than that of oxidation. If in a third experiment, besides having 

 proper temperature and chemical conditions, we produce the oxidation 



