THE CONTROL OF THE RESPIRATION 



353 



The increase in the carbonate ion HC0 3 ion itself might also serve as 

 a stimulus. That such is actually the case was demonstrated by 

 finding that, if the C H of the blood was first of all lowered by injecting 

 alkali intravenously, hyperpnea still developed in proportion as the CO., 

 accumulated in the inspired air; and that C H of the blood, when the 

 hyperpnea was at its highest, was below that of normal blood. Some 

 other factor than C H must obviously be responsible for this result. This 

 must be the HCO, anion. 



THE EFFECT OF REBREATHING CARBON DIOXIDE ON THE MINUTE VOLUME AND ON THE 



H-ION CONCENTRATION AND TOTAL CARBONATE CONTENT OF THE ARTERIAL 



BLOOD IN THE DECEREBRATE CAT 



*PH is the actual value given in the table. This is inversely proportional to CH. 



Further corroboration of the claim that the HC0 3 anion has a specific 

 stimulating effect on the respiratory center that is independent of C H , 

 has been furnished by Hooker, Wilson and Connett. 23 These authors 

 succeeded in keeping the centers of the medulla alive by perfusion with 

 defibrinated blood through the blood vessels of the brain, and found 

 that, although the respiratory movements of the diaphragm became de- 

 pressed with a decrease and excited with an increase in C H of the per- 

 fused fluid, a greater activity of the center was produced when this con- 

 tained a high tension of C0 2 than with another fluid of the same C H 

 but with a low tension of C0 2 . We conclude that, although the C K is the 

 important respiratory hormone, the carbonate ion (HC0 3 anion) also has 

 a stimulating influence. 



