I have been borne out in this by friends who have seen horses, camels, mules and other large animals in the coupling season. What is more absurd, for instance, than to say that an entire _penetrates_ the mare? His penis is a sensitive, beautiful piece of mechanism, which brings its light head here and there till it touches the right spot, when the mare, _if ready_, takes it in. An entire's penis could not penetrate anything; it is a curve, a beautiful curve which would easily bend. A bull's, again, is turned down at the end and, more palpably still, would fold on itself if pressed with force. The womb and vagina of a beautiful and healthy woman constitute a living, vital, moving organ, sensitive to a look, a word, a thought, a hand on the waist." A well-known American author thus writes in confirmation of the foregoing view: "In nature the woman wooes. When impassioned her vagina becomes erect and dilated, and so lubricated with abundant mucus to the lips that entrance is easy. This dilatation and erectile expansion of vagina withdraws the hymen so close to the walls that penetration need not tear it or cause pain. The more muscular, primitive and healthy the woman the tougher and less sensitive the hymen, and the less likely to break or bleed. I think one great function of the foreskin also is to moisten the glans, so that it can be lubricated for entrance, and then to retract, moist side out, to make entrance still easier. I think that in nature the glans penetrates within the labia, is withstood a moment, vibrating, and then all resistance is withdrawn by a sudden 'flashing open' of the gates, permitting easy entrance, and that the sudden giving up of resistance, and substitution of welcome, with its instantaneous deep entrance, causes an almost immediate male orgasm (the thrill being irresistibly exciting). Certainly this is the process as observed in horses, cattle, goats, etc., and it seems likely something analogous is natural in man." While it is easily possible to carry to excess a view which would make the woman rather than the man the active agent in coitus (and it may be recalled that in the Cebidæ the penis, as also the clitoris, is furnished with a bone), there is probably an element of truth in the belief that the vagina shares in the active part which, there can now be little doubt, is played by the uterus in detumescence. Such a view certainly enables us to understand how it is that semen effused on the exterior sexual organs can be conveyed to the uterus.