48 



ELECTROLYTES IN BIOLOGICAL SYSTEMS 



experiments were done involving iodoacetate and arsenate. In the one the cells 

 were exposed to the two agents simultaneously in the dark, while in the other 



SODIUM 



Fig. 9. Influence of light and running sea water on the sodium content of Ulva i)reviously 

 maintained for 16 hours in sea water containing o.ooi m/1. iodoacetate in the dark. Zero time 

 on the graph represents time of transfer to running sea water and light. Control samples 

 were illuminated after 16 hours in the dark. 



POTASSIUM 



SODIUM 



40 



30 



EC- 



ID 



< 



in _ _ 



40 



S 30 



r- 20 



10 



ui < 



< < < 



Fig. 10. Protection by arsenate against the potassium loss caused by iodoacetate in the 

 dark. Triplicate samples were removed after 13 hours under the conditions described on the 

 graph {Ulva). 



arsenate was added to algae which had been exposed to iodoacetate in the dark 

 for 18 to 20 hours. The results are shown in figures 10 and 12. In figure 10 it is 

 seen that arsenate alone under the conditions employed had no effect on either 



