RALPH S. LILLIE 793 



layer or plasma membrane in pure solutions of Na salts is of a kind 

 which is consistent with this interpretation, since the essential fea- 

 ture of the effect produced is an increase of permeability, allowing 

 the ready penetration of water-soluble substances (sugars, neutral 

 salts, etc.) to which previously the membrane formed a complete 

 barrier.2^ 



SUMMARY. 



The jelly surrounding the eggs of the starfish, Asterias forbesi, 

 is insoluble in normal sea water, but rapidly swells and dissolves 

 when the eggs are washed in a pure isotonic solution of NaCl. In 

 the presence of a small proportion of CaClo this solvent and disin- 

 tegrative action of the NaCl solution is entirely prevented, and in 

 the mixed solution the jelly exhibits the same insolubility and other 

 properties as in normal sea water. 



2. This action of CaClo in preventing the dissolution of the jelly 

 runs parallel with its action in preventing certain definite effects 



many resemblances to plasma membranes in their osmotic properties, especially 

 in their slight permeability to soluble inorganic salts and sugar, and suggests 

 that these phosphates may play a part in determining the properties of the m.em- 

 branes of cells. This possibiHty should not be overlooked, although the above 

 evidence indicates that insoluble salts formed with the colloidal compounds of 

 the cell are of chief importance. 



^^ Apparently the biologically essential properties of an organic membrane are 

 referable chiefly to those of the limiting surface layers. Hence the cases of salt 

 antagonisms at metaUic and other surfaces have also an intimate bearing on the 

 present problem. Bredig and Weinmayr (Z. physik. Chem., 1903, xlii, 601) cite 

 cases of such influence in the Hg-H202 catalysis; thus KOH and KCl may act 

 as antagonists; the rhythm is extinguished by adding KCl and is restored by KOH. 

 Related phenomena are seen in the influence of cations of high oxidation potential, 

 like Ag, in preventing the spontaneous activation of passive iron in solutions of 

 NaNOa and similar salts (Lillie, R. S., Science, 1919, 1, 416). Evidently the per- 

 meability and electromotor properties of any interfacial film depend on its com- 

 position and physical condition, both of which vary with the internal composition 

 of the two adjoining phases. Both physical and chemical factors are concerned 

 in the formation of the plasma membrane; adsorption, by which (presumably) 

 the surface materials are assembled, is usually classed as a physical process; but 

 the special composition of the membrane depends on the specific character of the 

 cell metabolism, and on the nature of the reactions (oxidations, etc.), occurring 

 at the cell surface. 



