Myelin x-ray patterns reconciled.

Two different X-ray diffraction patterns have been published for frog sciatic myelin. Here the apparent discrepancy is attributed to different spacings between the myelin membranes in the two experiments. Assuming the single membrane has the same structure in the two cases, some restrictions on the phasing are indicated. Several possible profiles for the single membrane are then considered. A profile derived by assuming a lecithin cholesterol-like bilayer within the membrane accounts for all the published data. Three published profiles also are considered. These are not quite in as good agreement with observation, but they cannot be excluded at present.