RESPIRATION 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 



20 30 40 f o TT TO go 9o 1 oo Oxidation 



17-5 C. no C0 2 



Reduction 



Oxidation 



37-5 C. no C0 2 



Reduction 



80 



60 



40 



20 



i 



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 COo. 

 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 and H contained 40 mm. Hg pressure of CO*. (From 

 Joseph Barcroft.) 



