The Davson–Danielli model (or paucimolecular model) was a model of the plasma membrane of a cell, proposed in 1935 by Hugh Davson and James Danielli. The model describes a phospholipid bilayer that lies between two layers of globular proteins and It is trilaminar and lipoprotinious.[1] The phospholipid bilayer had already been proposed by Gorter and Grendel in 1925;[2] however, the flanking proteinaceous layers in the Davson–Danielli model were novel and intended to explain Danielli's observations on the surface tension of lipid bilayers (It is now known that the phospholipid head groups are sufficient to explain the measured surface tension[3]). The Davson–Danielli model predominated until Singer and Nicolson advanced the fluid mosaic model in 1972.[4] The fluid mosaic model expanded on the Davson–Danielli model by including transmembrane proteins, and eliminated the previously-proposed flanking protein layers that were not well-supported by experimental evidence.