150 



therefore, not oiohig to a specifically radio-active potassium-action 

 but only to the long known potassinm-calcinm antagonism. 



3. The intliience of the K-ion concentration upon the permeability 

 of tiie vessel-wall (mentioned sub 1 and 2) coincides with an 

 influence upon the capillary lumen. A j)erfusion of the vascular 

 system of the frog with a mixture of NaCl 0.6 Vo H-CaCl, . 6 aq 

 0.01 7o produces so considerable a constriction of the vessels that 

 no fluid can pass through any more. Wken to this mixture a little 

 KCl, say, 0.01 7o ^^^^ ^-^ added, the vessels dilate and the fluid 

 runs on as before. This process is reversible. 



4. The parallelism of decrease of permeability and of constriction 

 of the vessel-wall manifests itself not only under the intluence of 

 Ca-ions, but also under that of oxygen. 



5. In a quantitative determination of the dilating and constiicting 

 action of {)hai'maca after Trendelenburg, due regard should be 

 paid in future to the ratio of Potassium- and Calcium-ions in the 

 circulating fluid. 



From the Physiological Laboratory of the 



5 March 1922. University of Groningen. 



ERRATUM. 



In these Proceedings of June 1912 (Vol. XV), p. 276, Table II, 

 column 5, line 12 from the bottom to replace the there printed 

 number 1.18908 by the number 1.69487. 



