The onset of labor probably is not purely accidental, and yet it is so inconstant in appearance and so indifferently early or late, that it has every appearance of being an affair of chance. The time when labor will come on is highly speculative in general, but the phenomenon is preceded by certain definite symptoms: The lightening. False pains. Show. Rupture of membranes. The pains. _Lightening._—About two weeks before labor, especially in a primipara, the uterus and the head sometimes descend into the pelvis. The body of the child falls forward and the abdomen protrudes, the stomach is flatter, the patient breathes easier and feels, as she says, “lighter.” But walking is more difficult, the bladder is stimulated to frequent evacuations and the rectum is compressed. This occurrence is a premonitory sign of labor, and also favorable inasmuch as it demonstrates that this particular head is not too large to pass this particular pelvis. _False pains_ may appear, especially in multiparas, from two to four weeks before labor. In some of these cases the pains may be due to gas or indigestion and respond to hot applications and enemas, or there may be definite uterine contractions, as shown by the hardness of that organ during a pain, but the phenomena are irregular and therefore not typical of labor pains. Usually they pass off in a few hours, but if the patient is nervous, the doctor or nurse may be called needlessly. The patient, therefore, should be instructed to have the pains timed by the watch for half an hour or an hour. If they are regular during this period, the physician should be notified. Upon his arrival, an internal examination will reveal the true character of the disturbance by the condition of the cervix and os. _The show_ is a discharge of thick, white mucus, slightly stained with blood. This is the mucus plug which occludes the cervix during pregnancy and when the os begins to dilate, the mass is released and passes out. Labor usually comes on vigorously within twelve hours. _The membranes_ may rupture before labor begins and much fluid escape. The advantage of the dilating bag of water and lubricating qualities of the liquor amnii are thus lost. Such a labor is called a “dry birth” and is frequently slow, exhausting, and extremely painful. _The pains_ are the subjective manifestations of the powers of labor. The forces concerned are uterine and abdominal muscles, principally assisted by those of the back, legs, and arms. Their constricting action on the nerve fibers in the walls of the uterus is the cause of the pains in the first stage. The onset may be violent and go on to a quick delivery, but generally the inception is more insidious. The _irregular_, _painless_ contractions, (of Braxton Hicks) that were mentioned on an earlier page, gradually at term change their character and become _regular_ and _painful_.