CARBONIC ACID 161 



ions. 1 Further, there is also reason to be- 

 lieve that the concentration of hydrogen and 

 hydroxyl ions may sometimes be concerned 

 in adjustments of great magnitude, which 

 involve the distribution of water between the 

 tissues and the body fluids, or at least be- 

 tween red blood corpuscles and the plasma. 2 

 Recently, for example, a theory has been sug- 

 gested which seeks to account for certain 

 forms of oedema as the result of local or general 

 increase in the acidity of the organism. 3 

 In any case, whatever the fate of these latter 



1 Henderson, Journal of Biological Chemistry, X, 3, 1911. 



2 The changing distribution of material between red 

 blood corpuscles and plasma as the tension of carbonic acid 

 changes has, since its discovery by Zuntz, been investigated 

 by a series of physiologists. (See Spiro and Henderson, 

 Biochemische Zeitschrift, 15, 114, 1908.) In each complete 

 cycle of the circulation there occurs a complete cycle of changes 

 between the constituents of the corpuscles and of the plasma. 

 As the blood passes through the tissues and receives carbonic 

 acid the volume of the red corpuscles increases from the 

 entrance of water coming from the plasma; chlorine simul- 

 taneously passes in the same direction ; and various other 

 changes occur. In the lungs, with the escape of carbonic 

 acid, the process is reversed. There seems to be no doubt 

 that this process is largely dependent upon changes in re- 

 action accompanying changes in the concentration of carbonic 

 acid. 



3 M. H. Fischer, "(Edema," New York, 1910. It is impos- 

 sible to judge of the correctness of many of the views set 

 forth in this work. At present they appear to be in part ill- 

 founded. 



