It is natural to ask what purpose is served by the pain associated with labor; and a moment's reflection will make it clear that one reason for the discomfort is the warning which it gives of the approach of birth. If the mother were not thus cautioned, she might be delivered under very awkward circumstances, and even under such conditions that occasionally the infant would perish the instant it was born. All mammals suffer in giving birth to their young, though with quadrupeds the period of suffering is shorter, for the upright posture of man has changed the shape of the pelvis, rendering birth somewhat more difficult. Anyone who observes the lower animals preparing for delivery will be convinced that they also are responding to pain, the most compelling call of nature. That the suffering is at all essential to the mother's love for her child I cannot believe. Under certain circumstances, as for example when the Cesarean operation is performed before the onset of labor, the delivery is painless; yet I have never known a mother less devoted to her child on that account. Biology throws no light upon the relation of the "curse of Eve" to present-day confinements. THE CAUSE OF LABOR.--It is evident that, in a general way, the muscular contractions of the womb cause the birth of the child; but before we thoroughly understand the act, science must discover what stimulates the muscle to contract. Although careful research has thus far failed to disclose the source and character of the stimulus, it has taught many properties of the contractions themselves. Their force has been measured and found to increase as the end of labor is approached; the pressure they exert varies between nine and twenty- seven pounds. We also know that the patient can neither hasten nor delay the contractions voluntarily. Strong emotions are believed to accelerate them at times, and we find a very extraordinary illustration of this effect recorded in I Samuel, IV, 19, where we read: "Phineas' wife was with child, near to be delivered; and when she heard the tidings that the ark of God was taken, and that her father-in-law and her husband were dead, she bowed herself and travailed; for her pains came upon her." On the other hand, and much more familiarly, excitement checks the contractions after they have begun. Every obstetrician has heard patients say that with his arrival the pains died down. Yet such an influence is never permanent; the contractions soon reappear, and labor advances as though no interruption had occurred. For the artificial induction of labor, the physician has at his disposal means that resemble the method sometimes employed by nature. Suitable appliances introduced into the womb provoke contractions, and labor proceeds step by step as if the stimulus were a normal one. Nature does not, however, ordinarily employ mechanical irritation to start the uterine contractions. The initial factor is more remote and, as I have said, is not yet well understood.