The study of membrane assembly has, until now, consisted of fractionating a membrane into its components or of assembling model membranes from non-physiological components. A native precursor to membranes was obtained as a quasi-crystalline material. It was the purpose of this work to develop the appropriate techniques for characterizing the material as well as to carry out the characterization. The results of the characterization indicate the quasi-crystalline material contains a single protein, structural protein. This protein is in two forms which may reflect two sequential steps in membrane assembly. One form is solubilized in 2-chloroethanol and isolated by gel filtration. The other form may be isolated on gel filtration only after previous release by alkaline hydrolysis. This work forms the basis of future study of membrane assembly in that it has developed solvents and compatible techniques for the preparation, identification and characterization of a native precursor of membranes.