Materials and Methods.-Splenic and/or liver tissues were obtained from six patients with Gaucher's disease, either at the time of splenectomy or at autopsy. These tissues were processed for light and electron microscopy, and were stored frozen. The thawed tissues could easily be prepared for negative staining by mincing small fragments in a solution of 1% ammonium acetate. Small drops of this solution were added to drops of 1% phosphotungstic acid, and 300-mesh coated and carbonized grids were used to sup-port the stained material. This process was equally satisfactory when applied to form-aldehyde-fixed tissues. Shadowing techniques were employed in order to determine the direction of the helix noted in negatively stained preparations. Shadowing was carried out in a vacuum evaporator, using carbon platinum shadowed at an angle of approximately 100. A Phillips 200 electron microscope was used throughout this study. Care was given during the printing phase of the shadowed forms in order to preserve the correct screw sense of the helix. 4

Density gradient centrifugation was carried out in order to separate the tubules from other cellular membranes. For this procedure, tissue was ground with 2.5 times the volume of Tris buffer (at pH 7.6) containing 0.35 M sucrose, 0.025 M KCl, and 0.01 Al MgCl2. After initial centrifugation for 10 min at 27,000 X g in a Sorvall centrifuge, 10 ml of the supernatant was carefully applied to a 30-ml centrifuge tube containing 10 ml of 1.5 Mf sucrose layered on 10 ml of 2.0 M sucrose. After centrifugation for 17 hr at 75,000 X g, the white layer that had collected between the 0.3 and 1.5 M sucrose was separately collected, pelleted, and resuspended in Tris buffer without added sucrose, and 2 ml was applied to a 15-ml continuous gradient solution ranging from 0.3 to 1.5 Al sucrose. The material was then centrifuged again for 17 hr at 78,000 X g. Thin-layer chromatography with a polar lipid solvent system (composition: 100 ml chloroform, 40 ml methanol, 6 ml distilled water) was carried out on the continuous gradient density fraction which contained predominantly tubular forms as determined by electron microscopy. Protein and phosphorus determinations were also performed on this fraction according to the methods of Lowry et al. 5 and Bartlett and Shin, 6'7 respectively. In an attempt to produce changes in the morphology of the cerebroside tubule, this fraction was also exposed overnight to 2.0 A urea, as well as to 1% triton, 0.1 N NaOH, and 0.1 N HCl. Results.-(1) Morphology: Tubular forms are easily identified as long forms in the negatively stained preparations of the mincedtissues or inthe gradient density fractions. Frequently, several tubules are twisted together. The individual tubules have a width varying from 250 to 500 A, and someattain a length of 5, i. Each tubule appears to be made up of 10-12 fibrils gently twisted about the long axis of the tubule. Shadowing techniques reveal a helix with a right-handed screw sense (Figs. 2 and 3). Adjacent tubules are often noted to be twisted about each other (Fig. 4).