“…Repeated studies in vitro of muscle strips of non-pregnant and pregnant uteriusing Magnus-Kehrer's methodwere carried out (Magnus, 1904, Kehrer, 1907, Genell, 1937, Runge, 1929, Adair and Haugen, 1939, Scott Russel, 1943, Sol Fernandez, 1951, Danforth, 1954, Gold-farb, 1954, Ingelman-Sundberg, Sandberg, Ryddn and Lindgren, 1954.…”