[Use of a zonal rotor for demonstrating that human myelin is formed by a continuum of particles of different densities].

Human myelin isolated from frozen brain consists of a continuum of particles as shown by sucrose continuous gradient (between 0,4 and 0,85 M) on zonal rotor. This was determined by measuring the O. D. at 260 and 280 millimicron, the protein concentration by Lowry method and sucrose concentration by polarimetry in 60 fractions. Most of the material is concentrated between 20-23% sucrose, the maximum being found at 21.5% (0.63 M). The fractions are dialyzed for 62 hrs. to remove the sucrose and the pellet obtained after centrifugation shows that the protein concentration increases from the ligher fraction to the heavier.