ELECTRON MICROSCOPY OF THE MACRONUCLEUS OF <i>EUPLOTES EURYSTOMUS </i>

Abstract

It has been demonstrated by Gall (1), Prescott and Kimball (2), and Kimball and Prescott (3) that the macronucleus of Euplotes is excellent material for studying relations between DNA, RNA, and protein synthesis during nuclear replication. Replication bands normally originate at the two tips of the long, rod-shaped macronucleus during the early hours of interphase and progress as two waves of DNA synthesis until they meet in the center. In the light microscope one sees that two marked changes in the cytological organization of DNA precede DNA replication.