Color enhanced electron micrograph of Kleinschmidt preparation showing molecular complexes resulting from the reaction of this DNA with E. coli RNA polymerase upon addition of the four regular nucleoside triphosphates: ATP, CTP, GTP, UTP. After fifteen minutes at room temperature characteristic convolutes formed by filaments of varying widths are found in close association with the DNA-enzyme copmlex. These correlated electron microscopic and biochemical studies, carried out in collaboration with Dr. Richard Bumport and Dr. Samuel Weiss at the University of Chicago, are expected to yield further information on the participation of RNA-polymerase in the differential RNA transcription upon DNA templates. Enhancement of 9a1962.