54 



ELECTROLYTES IN BIOLOGICAL SYSTEMS 



the generation of high energy phosphate bonds (4, 23). Figures 13 and 14 indi- 

 cate the net movements of potassium and sodium in Ulva treated^ with 

 3.3 X io~^ m/1. DNC in the dark over a period of 48 hours. Again it is to be 



POTASSIUM 



^2iIl£2i-DARK • 



20 30 



- HOURS - 



SODIUM 



100 T 



90 

 80 

 70 H 

 60 

 50 

 40 H 

 30 

 20 



10 



20 30 



- hours- 



Figs. 13 {top) and 14. Influence of 4,6-clinitro-o-cresol (DNC) on the potassium and 

 sodium contents of Viva lactuca. 



noted that the kinetics of potassium loss are distinctly different from those of 

 sodium uptake in the presence of this 'decoupling agent'. It should be pointed 

 out that these experiments were carried out in the dark not because DNC 

 does not cause these ion shifts in the light (as is the case with iodoacetate) 

 but rather because DNC is an effective inhibitor of photosynthesis. Thus the 



