Ovulation in the normal rabbit is dependent upon copulation (Heape, 1905). Since the same correlation is found with grafted ovarian tissue, as shown by Friedman (1929
a
) and previously found by Asdell (1926), the stimulus (presumably nervous in nature) set up by coitus does not act directly upon the ovary. In view of the part which the anterior pituitary body is now known to play in controlling ovulation (Zondek and Aschheim, 1927, Smith and Engle, 1927) it is natural to suppose that copulation stimulates the anterior pituitary, which in turn reacts upon the ovary to cause ovulation. It has, in fact, been shown that hypophysectomy of the rabbit within I hour after copulaion inhibits the ovulation which would normally occur 10—12 hours later (Fee and Parkes, 1929). Furthermore, Bellerby (1929) was able to induce ovulation in the unmated œstrous rabbit by the injection of acid extracts of anterior pituitary tissue. Later, Friedman (1929
b
) obtained the same result with extracts prepared from urine of pregnant women. Both of these authors were able to obtain the effect by one injection, and the influence of this on administration of hormone must have passed off by the time of ovulation. Neither author, however, appears to have studies the subsequent history of the follicle caused to ovulate without the preceding influence of copulation and free from the extraneous stimulus of further injection. It is evident that such a study would indicate something of the factors concerned in initiating the stimulus (presumably hypophyseal in origin) responsible for the luteinisation of the ruptured follicle.
Reinstatement of short-latency responses after asymptotic Pavlovian conditioning training by the presentation of an extraneous stimulus
