STRUCTURE OF NERVE CELL MEMBRANES 159 



face. The barrier concept of permeability, which is required for a membrane 

 with phase boundaries, differs distinctly from that of diffusion through a con- 

 tinuous phase. It has been expounded by Danielli (1952) and more recently in 

 much greater detail by Zwolinski, Eyring and Reese (1949) and Polissar (1954). 



Thus it seems that the laminar cell membrane with a lipid phase is capable 

 of exhibiting quite a few of the known properties of excitable membranes, and 

 it merits serious consideration until positive evidence against it is found. 



Lastly, I would like to ask Dr. Mullins whether he considers it possible that 

 the cell membranes could consist of two sheets of his protein columns attached 

 to a central lipid layer? 



References 



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Davson, H. and J. F. Danielli. 1952. The Permeability of Natural Membranes. Cam- 

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Gasser, H. S. 1955. J. Gen. Physiol. 38: 709. 



Geren, B. B. 1954. The formation from the Schwann cell surface of myelin in the pe- 

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Hodgkin, A. L. and B. Katz. 1949. The effect of sodium ions on the electrical activity 

 of the giant axon of the squid. J. Physiol. 108, 37. 



Johnson, F. H., H. Eyring and M. J. Polissar. 1954. The Kinetic Basis of Molecular 

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Ling, G. N. 1952. The Role of Phosphate in the Maintenance of the Resting Potential 

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Lorente de No, R. 1947. Studies from the Rockefeller Inst, for Med. Res. 131, 41. 



Lucke, B., H. K. Hartline and R. A. Ricca. 1939. Comparative permeability to water 

 and to certain solutes of the egg cells of three marine invertebrates. J. Cell. Comp. 

 Physiol. 14, 237. 



McBain, J. W. 1950. Colloid Science. Chapt. 17. D. C. Heath and Co. 



Rideal, E. K. 1925. On the influence of thin surface films on the evaporation of water. 

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Schmitt, F. O., R. S. Bear and K. J. Palmer. 1941. X-ray diffraction studies on the 

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Shanes, A. M. and D. E. S. Brown. 1942. The effect of metabolic inhibitors on the rest- 

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Sjostrand, F. S. 1953. Electron microscopy of mitochondria and cytoplasmic double 

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Dr. Morales: I am inclined to agree with Dr. Mullins that his view is not 

 seriously embarrassed by demonstrating that there is a similar qualitative effect 

 of narcotic agents on the interior bodies of the cell. 



