In Euplotes a replication band of the macronucleus has larger heterochromatin masses on one side of the band after DNA replication has occurred. The replication band moves in the direction of lighter staining in the macronucleus. Vacuoles containing concretion bodies are observed. TEM taken on 8/03/67 by R. Allen with Philips 200 operating at 60kV. Neg. 7,200X. Standard glutaraldehyde fixation followed by osmium tetroxide, dehydrated in alcohol, and embedded in an epoxy resin. Microtome sections prepared at approximately 75nm thickness. The raw film was scanned with a Nikon Coolscan 9000ED. This image is suitable for quantitative analysis. Additional information is available at (http://www5.pbrc.hawaii.edu/allen/).