A NEW TYPE OF ARTIFICIAL CELL SUITABLE FOR 

 PERMEABILITY AND OTHER BIOCHEMICAL 



STUDIES 



E. NEWTON HARVEY 

 (Physiological Lahoratory, Princeton University) 



Research on the permeability of membranes has been largely 

 confined to a study of the properties of what may be termed macro- 

 scopic membranes; composed of parchment, collodion, rubber, or 

 silk impregnated with various substances. The best example of 

 membranes of a type and size comparable to the surface film of cells 

 and yet available for permeabiHty studies are the precipitation 

 membranes of Traube, investigated by Waiden, Tamann, and 

 Meerburg. 



Protein membranes of exceeding fineness are formed at the 

 surface of various non-miscible fluids shaken with protein Solutions, 

 such as the surface film of oil globules in protein-oil emulsions, or 

 the films formed on Chloroform or benzol when shaken with albu- 

 men Solutions.^ Such membranes are useless for permeability 

 studies so long as they Surround fluids that do not mix with water. 

 However, it is an easy matter to replace the fluid within the mem- 

 brane by a watery Solution, provided the former fluid is readily 

 volatile and slightly soluble in water. Chloroform conforms to 

 these conditions. When Chloroform is shaken with egg albumen 

 Solutions, the globules, in the course of 10-15 minutes, shrink in 

 size and their membranes become crumpled, due to the passage of 

 Chloroform from water to air and from globule to water. Lecithin, 

 if previously dissolved in the Chloroform, will take up water as the 

 Chloroform passes out. In the course of one to two hours, in an 

 open vessel, all the Chloroform disappears and we obtain, instead 

 of a Chloroform Solution of lecithin, a water Solution of lecithin 

 enclosed in a fine protein membrane, the whole of a size comparable 

 with cell sizes. The diameter of the droplets may be varied at will 



^ Robertson : Journal of Biological Chemistry, 4, p. i, 1908. 



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