Electron micrograph of a thin section of fixed, embedded stained cells of Peranema trichophorum. Shown is a section of the "rodorgan', a bundle of 13-protofilment microtubules with pseudo-hexagonal symmetry. The section thickness was approximately 400 angstroms(silver grey section). Image recorded on Kodak SO-163 film, developed in straight D-19 developer, scanned on a Perkin-Elmer Model 1010G microdensitometer with a step size of 25 microns. Original electron-optical magnification was 46000. Sample was fixed in 2.5% glutaraldehyde, stained with Osmium tetroxide, dehydrated, embedded in Spurr's epoxy resin, sectioned, then stained with uranyl acetate and lead citrate. The rodorgan is thought to be used by Peranema for disrupting the microorganisms that are its prey. Unpublished micrograph