An image of the pellicle of Didinium, in cross section of a non-dividing cell, has a plasma membrane with a distinct glycocalyx on its external surface and a flattened alveolar sac system. Under the alveoli are one or two or more ribbons of microtubules in ridges between the more corrugated mucocyst docking sites. Mitochondria with tubular cristae lie under the epiplasm in the ribosome filled cytosol. TEM taken on 2/18/69 by R. Allen with Philips 300 operating at 60kV. Neg. 20,500X. Bar = 0.5µm. The negative was printed to paper and the image was scanned to Photoshop. This digitized image is available for qualitative analysis. A raw, unprocessed, high resolution version of this image (CIL:9927) is in the library and available for quantitative analysis. Standard glutaraldehyde fixation followed by osmium tetroxide, dehydrated in alcohol and embedded in an epoxy resin. Microtome sections prepared at approximately 75nm thickness. Additional information available at (http://www5.pbrc.hawaii.edu/allen/).