Membrane

boundary of a cell, organism, organization

A membrane is a Layer of material which serves as a selective barrier between two phases and remains impermeable to specific particles or group of particles or substances when exposed to the action of a driving force. Some components are allowed passage by the membrane into a permeate stream, whereas others are retained by it and accumulate in the retentate stream. http://en.wikipedia.org/wiki/Membrane

2006-10-25-WilliamOdeoMbo