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 CH 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 experimental alteration of 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 

 CH 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 (cols. 8 and 14), 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 (cols. 9 and 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 in the -blood removed after the animal had 

 breathed for a few minutes in outside air (col. 16) when the C0 2 content 

 likewise returned (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. 



