It has been my privilege and pleasure during the past half century to participate in the unfolding of present-day concepts of the mammalian female reproductive cycles. When the studies recorded here began in the late 1930s it was already established that cyclic ovarian function is governed by gonadotropic secretions from the anterior pituitary gland, the "conductor of the endrocrine orchestra," and that in turn this activity is importantly dependent in some way upon secretion of estro gens and progesterone by the ovaries. Although a role of the nervous system was recognized for the...