Mosaic Collodion Membranes as Analogues of the Plasma Membrane

Dense collodion membranes have been prepared, both plain, and with the addition of triphenyl guanidine. The latter membranes yield relatively permanent concentration E.M.F.S opposite in sign to those obtained with plain membranes, and of magnitudes approaching the limits predicted for membranes permeable to anions but not to cations. Such membranes were arranged in pairs to give non-living models analogous to the hypothetical mosaic plasma membranes of living cells. They failed either to accumulate or exchange ions except traces of chloride, because the plain collodion membranes were practically impermeable to potassium as well as to anions, and the triphenyl guanidine collodion membranes were impermeable to cations and barely permeable to chloride.