Even although the different organs, both near and remote, may have accommodated themselves to the changes in the uterine action, in the commencement of gestation, the proper balance may yet be lost at a subsequent period; and this is most apt to take place about the end of the third, or beginning of the fourth month, when the uterus is rising out of the pelvis; and hence a greater number of abortions take place at that time than at any other stage of pregnancy. There is from that time, to the period of quickening, a greater susceptibility in the uterus to have its action interrupted, than either before or afterwards, which points out the necessity of redoubling our vigilance in watching against the operation of any of the causes giving rise to abortion from the tenth to the sixteenth week. If the uterus, in its unimpregnated state, become very torpid, as in some cases of amenorrhœa, the abdominal muscles sometimes have their action much increased; and there is absolutely an attempt made to expel it, violent paroxysms of contraction coming on, and repeated daily for a length of time. These may be lessened by opiates, but can only be cured by exciting the natural action of the uterus. I mention this fact, from its singularity, although it do not immediately refer to abortion. If the action of gestation go on under restraint, as, for instance, by a change of position in the uterus, or by its prolapsing too low in the vagina, it is very apt to be accompanied by uneasy feelings, for, whenever any action is constrained, sensation is produced. The woman feels irregular, and pretty sharp pains in the region of the uterus, and from sympathetic irritation both the bladder and rectum may be affected, and occasionally a difficulty is felt in making water, by which a suspicion is raised that retroversion is taking place. Sometimes the cervical vessels in these circumstances yield a little blood, as if abortion were going to happen; but by keeping the patient at rest, and attending to the state of the rectum and bladder, no harm is done: and when the uterus rises out of the pelvis, no farther uneasiness is felt. Retroversion of the uterus likewise constrains very much its action, and may give rise to abortion, though in a greater number of instances, by care, gestation will go on, and the uterus gradually ascend. Sometimes in irritable or hysterical habits, the process of gestation produces a considerable degree of disturbance in the actions of the abdominal viscera, particularly the stomach, exciting frequent and distressing retching or vomiting, which may continue for a week or two, and sometimes is so violent, as to invert the peristaltic motion of the intestines near the stomach, in which case feculent matter, and, in some instances, lumbrici, are vomited.