“…Robson and Illingworth [1932], however, investigated the hormone content of four placentee removed at various stages during gestation and were unable to demonstrate in them any progestational or inhibitory hormone. Similar negative results have been recorded by C 1 a ub e r g, Thiel and Ziecker [1932]. From the evidence at present available it seems more likely that the changes in reactivity in the human uterus after the early stages of gestation are not primarily dependent on luteal hormones.…”