THE CONTROL OF THE RESPIRATION 



369 



air runs approximately parallel with the increase in the C H of the blood, 

 but on account of the experimental difficulties encountered they could not 

 decide whether changes in C H are alone responsible for the effect. These 

 authors had previously demonstrated that changes in C H can be induced 

 in blood removed from the body by alterations in the C0 2 tension within 

 the physiological limits. An increase of one millimeter in C0 2 tension 

 was found to cause an increase in C H of 0.0065 x 10' 7 (see page 27). 



R. W. Scott's experiments, above referred to, have, however, yielded 

 more definite results. By using the colorimetric method for determining 

 C H of the blood (see page 32), it could be readily shown, as is evident 



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. 



from the table (col. 8 in table), that a marked rise in C H became evident 

 when the inspired air contained 5 per cent or more of C0 2 . That this 

 rise was due to increase in the C0 2 tension was shown not only by finding 

 a greater percentage of C0 2 (col. 15) in the blood, but also by being able 

 to demonstrate that when C0 2 -free air was bubbled through the blood 

 removed during the dyspnea, C H immediately returned to the normal, 

 which it also did when the blood removed after the animal had breathed 

 for a few minutes in outside air (col. 16). The C0 2 content likewise re- 

 turned (col. 17). Had the increase in acidity been caused by nonvolatile 

 acids lactic, for example these results, particularly the latter, could 

 not have been obtained. 



