“…The nucleosides and nucleotides studied so far are 5'-bromo-5'-deoxythymidine (Huber, 1957), calcium thymidylate (Trueblood, Horn & Luzzati, 1961), a cyclonucleoside (Zussman, 1953), cytidine (Furberg, 1950), cytidylic acid b (Alver & Furberg, 1959, Sundaralingam & Jensen, 1963, adenosine 5'-phosphate (Kraut & Jensen, 1963), 5-fluoro-2'-deoxyuridine (Harris & Macintyre, 1964) and 5-iodo-2'deoxyuridine (Camerman & Trotter, 1964). Of these, the structures of cytidylic acid b, 5-fluoro-2'-deoxyuridine and adenosine 5'-phosphate are the most accurately determined, having standard deviations in bond lengths and angles of the order of or less than 0.01 It and 1 o respectively.…”