SURFACES 39 



The antagonistic effects exerted by electrolytes of these two opposing 

 groups appear to correspond sufficiently closely with those observed 

 by OSTERHOUT in experiments on living cells to suggest the possibility 

 that variations in permeability exhibited by protoplasm under the 

 influence of various salts might be attributable at least in part to 

 reversible transformations of the marginal layer of protoplasmic 

 material between systems in which a non-aqueous phase is dispersed 

 in an aqueous, which would be relatively freely permeable to water, 

 and the reverse type of system in which an aqueous phase is more or 

 less surrounded by a non-aqueous film which would be impermeable 

 or relatively less permeable to water. 



A Traube capillary pipette was employed to study the influence 

 exerted by given salts individually, and in combination, on the rela- 

 tive degree of dispersion of interfacial soap films in oil and water. 

 Aqueous solutions containing caustic soda or soap and various con- 

 centrations of the salts to be tested were allowed to flow from the 

 capillary pipette through neutral oil or oil containing free fatty acid, 

 and the number of drops produced served as an index of the dis- 

 persing or protective effect exerted by the electrolytes in question 

 on the interfacial soap film. Those electrolytes which possess a 

 readily adsorbed anion appear to cause an increase in the number of 

 drops, which corresponds with a lowering of the surface tension of 

 the water phase, a destruction of the surface film, and an increased 

 permeability of the system to water. Those electrolytes which 

 possess a readily adsorbed cation exert the reverse effect, diminish- 

 ing the number of drops, which indicates diminished dispersion or 

 destruction of the film and a diminished permeability of the system 

 to water. For example, a 0.001-m NaOH passed through olive oil 

 gave 44 drops; the addition of NaCl to a concentration of 0.15 m 

 raised the number of drops to 300; the addition of CaCl2 at a concen- 

 tration of 0.00 15-ra lowered the number of drops to 24; while a 

 system in which 0.001-m NaOH was employed in conjunction with 

 0.15-m NaCl and 0.0015-m CaCl 2 gave 44 drops, corresponding 

 with the original system and indicating that under the conditions of 

 the experiment NaCl and CaCl 2 exert an antagonistic or compensa- 

 tory effect upon one another in the molecular ratios of 100 : 1. 



In similar experiments with other electrolytes, anesthetics, etc., the 

 ratios in which antagonistic effects were produced corresponded 

 sufficiently with those in which the substances in question exerted 

 antagonistic effects on marine and other organisms as to suggest the 

 possibility that these physical systems may afford a crude model of 

 the mechanism underlying the control of permeability in protoplasm. 

 Salts of magnesium and other substances which exhibit abnormalities 



