The bag of waters now descends, and enlarges more and more, until at last, being unable any longer to bear the strain to which it is subject, it bursts, and the waters flow away in a profuse gush. Immediately this takes place the head descends, and closes up the passage; the pains cease for a time, and the patient again has a respite, while the uterus apparently gains fresh power. Very soon the contractions recommence, more energetically even than before, the head passes the mouth of the Womb and enters the Vagina, which keeps enlarging as it descends, till it reaches the lower part, or floor of the pelvis. The pains now become more violent than ever, the patient screams with agony, clutches hold of any object near her, throws herself back, draws in her breath, and bears down with all the force she can command. The fearful cries which most females emit at this time appear to assist the delivery, by the convulsive efforts at breathing which they necessitate, and the expulsive straining also does the same. These natural efforts are much assisted by providing a firm support for the patient's feet, against which she can push, which she will do with tremendous force. The head now presses, at each pain, against the perineum, which begins to project outwards, as also does the Rectum. The Vulva begins to dilate, the lips separate wider and wider, and part of the child's head becomes visible. Gradually the lips become thinner and thinner, and at last disappear nearly altogether, so that the mouth of the Vulva is only composed of thin ring, which seems ready to give way every moment. The head however recedes, and the parts again assume something like their natural condition for a short time, when the same process again takes place, and the distension proceeds still further, while the head does not retire so far. This alternate action is repeated perhaps many times, so that the external mouth is opened gradually, and without the lips or perineum being torn, which they would be if the head were to pass suddenly, before they were softened and dilated. After this has been continued for a sufficient period a strong expulsive pain is felt, the female screams, the head passes clean through the external opening, and the lips close round the neck. This however, is only for an instant, the rest of the body speedily following the head, in the manner hereafter to be explained. Most usually, in fact, the whole body follows the head without any stoppage at all, but sometimes there is a delay of a few seconds. _The Third period of delivery_ comprises the delivery of the Placenta, which will occupy our attention in another place.