LIBRARY 

 W YORK 

 b*J rANICAL 



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Reprinted from Science, pages 694-690. Vol. 



LVH, No. 1485, June 15, 1923 



PHASE REVERSAL IN PROTOPLASM AND 

 EMULSIONS 



The reversal of phases in oil emulsions by 

 electrolytes was discovered by Clowes. 1 Clowes 

 worked with olive oil emulsions in which the 

 aqueous phase was a soap solution, the soap 

 being added directly or formed through saponi- 

 fication of the oleic acid in the olive oil by an 

 aqueous phase of NaOH. Clowes found that, 

 when the salt of a bivalent cation (CaCte) is 

 in excess in the aqueous phase, the emulsion is 

 of the water-in-oil type, and when the hydroxide 

 of the monovalent cation Na is in excess, the 

 emulsion is of the oil-in-water type. Clowes 

 came to some very interesting and far reaching 

 conclusions on the basis of his experiments. It 

 does not appear that he worked with emulsions 

 in which the stabilizing agent is some colloid 

 other than soap. 



Clowes saw in the behavior of oil and water 

 emulsions (in which soap is the emulsifier) an 

 explanation of changes in protoplasmic perme- 

 ability. It is now believed (by some biologists) 

 that monovalent cations increase permeability 

 of the plasma membrane, while bivalent cations 

 decrease permeability. The hydroxide of the 

 monovalent cation Na produces in an oil emul- 

 sion (with a soap stabilizer) a system in which 

 the continuous phase is water. Such a system 

 would be readily permeable to water soluble sub- 

 stances. Salts of bivalent cations, such as 

 <#- CaCte, produce an emulsion in which oil is the 



continuous phase. Such a system would be im- 

 permeable to water soluble substances. 



— 4 



i — I i Clowes, G. H. A., "Protoplasmic equilibri- 



rr um," Jour. Phys. Chem., 1916, xx, 407-451. 



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