The causes of pathologic and accidental abortion are very numerous and often interactive. They may arise from the fetus, the mother, the father, or from violence. The death of the fetus, or diseases of the fetus itself or of its appendages, cause abortion. Weakness of the fetus from alcoholism in the parents, anemia, carbon monoxide and lead poisoning, tobacco poisoning in women who are cigar-makers, and similar conditions in one or both parents, will bring on abortion. Monsters rarely go on to term. Acute or chronic affections in the mother, as typhoid, malaria, smallpox, cholera, scarlatina, measles, tuberculosis, and the like, and syphilis in the mother or father, effect abortion. Other abnormal states that bring on abortion are low blood-pressure in maternal anemia, shock, syncope; hemorrhages into the placenta in maternal nephritis; hemorrhages between the placenta and uterus from diseases of the placenta and decidua, or from traumatism, which detach the placenta; sun or heat stroke; sudden high temperature in fever; toxemias, as in some forms of hyperemesis gravidarum, eclampsia, chorea, hepatic autolysis, and impetigo herpetiformis. Chronic endometritis, or inflammation of the lining membrane of the uterine cavity, is the commonest maternal cause of abortion, especially of habitual abortion. In this condition hemorrhages in the decidua, or uterine fold that holds the fetus, kill the fetus, or force the ovum off the uterine wall, or excite expulsive uterine contractions. Without hemorrhage endometritis prevents a firm fixation of the ovum, or it may bring about a malposition of the placenta, called placenta praevia. Endometritis at the decidua may cause hydrorrhoea gravidarum, and the accumulated serous secretions from this source are likely to start uterine contraction. Chronic metritis, or inflammation of the deeper tissues of the uterus, is commonly found with endometritis, and it prevents the expansion of the uterine muscle. This condition is more likely to cause abortion than endometritis alone. Acute gonorrhea, inflammations of the Fallopian tubes, and appendicitis sometimes interrupt pregnancy. Other causes are malformations and diseases of the uterus, infantilism, fibroids, polyps, uterine horns, lacerations and amputation of the cervix, and retroversions and retroflexions of the uterus. At times a replacement of the uterus will avert an abortion.