KESPIRATION BEYOND THE LUNGS 



387 



gas apparatus. To obtain the rate of oxidation, a mixture of N 2 or H 2 

 and 2 is bubbled through the blood with the partial pressure of the 

 2 the same as that which obtains in alveolar air namely, about 95-100 

 mm. Hg; and to obtain the rate of reduction pure N 2 or H 2 gas is bub- 

 bled through. 



The rates of reduction or of oxidation as thus determined are then 

 plotted in curves constructed with the percentage saturation of the 



100, 



1? Oxidation 



17-5 C. no CO, 



Reduction 



100 



Oxidation 



37-5 C. no C0 2 



Reduction 



80 



60 



20 



V 



Oxidation 



37-5 C. 



+ 40 mm. pressure 

 ofC0 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.) 



