JACQUES LOEB 687 



order Cl< Br< I (being largest in I), while for monatomic, monovalent 

 cations it increases in the order Li< Na< K< Rb (being largest in 

 Rb). 



3. It is shown that the accelerating as well as the depressing effect 

 of the anions mentioned increases directly with the order of magni- 

 tude of their radius and that the efficiencj^ is greatest in the case of I 

 which has the largest radius; while the accelerating as well as the de- 

 pressing effect of cations increases inversely with the order of miagni- 

 tude of their radius, Li with the smallest radius having the greatest 

 efficiency. 



4. This is intelligible on the assumption that the action of the ions 

 is electrostatic in character, in the case of cations due to the electro- 

 static effect of the excess charge of their positive nucleus, and in the 

 case of anions due to the excess charge of their captured electron. 

 The electrostatic effect of the positive nucleus of a cation on the 

 membrane (or any other body) will be the greater the smaller the 

 ionic radius of the cation; and the electrostatic effect of an excess 

 electron will be the greater the further its distance from its own posi- 

 tive nucleus. 



5. It is suggested that this rule may possibly include polyatomic, 

 monovalent ions {e.g. NO3, CNS, etc.) when we replace these poly- 

 atomic ions by monatomic models in which the radius is calculated 

 in such a way as to give the model the same electrostatic effect which 

 the polyatomic ion possesses. 



6. These conclusions are in harmony with the fact that the efficiency 

 of ions increases also with their valency. 



7. It is suggested that these rules concerning the influence of the 

 ionic radius can possibly be demonstrated in other phenomena, depend- 

 ing on the electrostatic effect of ions. 



