Abstract
In most mammals ovulation is a spontaneous event, but as first pointed out by Heape in some species, including the rabbit, the European ferret (Mustelus putorius), and the domestic cat, ova are discharged from the ovary only after copulation. Such observations as these make it necessary to know the exact facts concerning each species which is used for experimental work. The common Indian monkey, Pithecus (Macacus) rhesus, for example is being studied extensively and used for experiments in the physiology of reproduction, but thus far the ripening and mature Graafian follicle has never been described, and no specific statement has appeared as to whether or not ovulation is spontaneous.
It is true that in the group reported by me in 1923, ovulation was shown to have occurred in females which were kept in a group with no males present, but this is not proof of strictly spontaneous ovulation because we know that ovulation may take place in rabbits kept in a common cage with other females without the presence of males. In such cases the stimulus to ovulation is provided by homosexual pseudo-copulation.
The erection in the summer of 1928 of new quarters for my colony, by aid of a fluid research fund granted to this school by the Rockefeller Foundation, permitted a direct experiment on this question.
On November 20, 1929, four fully mature female Rhesus monkeys were placed in separate cages. The animals were placed in isolation in a series of cages separated from each other by heavy wire netting.
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