When the mother has an infectious disease like typhoid, smallpox, cholera, or typhus, the infection may reach the fetus and kill it, or may cause an endometritis with a hemorrhagic tendency. Maternal sepsis may kill the fetus directly or secondarily, and this is true also of maternal syphilis. A sudden rise in temperature may excite expulsive uterine contraction. In pneumonia the excess of carbon dioxide in the blood may bring on abortion. Like pneumonia, anesthesia may kill the fetus if kept up for a long time, or if marked by cyanosis. Prolonged nitrous-oxide anesthesia is especially dangerous to a fetus, but a brief nitrous-oxide anesthesia for the extraction of a tooth may not bring on abortion. The worst tooth stump can be extracted painlessly after local injection of novocain, with no danger to the fetus. The gums remain somewhat sore for a day or two after novocain infiltration, but this inconvenience is a much less evil than total anesthesia, even when there is no pregnancy. It is probable that total anesthesia is morally unjustifiable for the extraction of a single tooth if the tooth is not wedged in. Violence, accidental or intentional, is a frequent primary or secondary cause of abortion. Sometimes a slight jar, a misstep on a stairway, a nervous shock, a jump from a carriage-step, lifting weights, running sewing-machines, sea-bathing, a rough automobile ride, will bring on an abortion where there is a predisposition. Often in healthy women, on the other hand, extreme violence does not interrupt pregnancy. Surgical operations are classed here with violence. In a neurotic woman a slight operation on an organ not directly connected with the uterus will start expulsive contractions. Again, 66 per cent. of operations on ovarian tumors during pregnancy have left the uterus undisturbed. De Lee says he has removed fibroids from the pregnant uterus, once even exposing the chorion, and has amputated the cervix of a gravid uterus, without interrupting pregnancy. Several cases have occurred where both ovaries have been removed during pregnancy without abortion. The breast has been amputated and a kidney removed from a pregnant woman[79] without disturbing the pregnancy. Wiener[80] did eleven operations for ovarian tumors during pregnancy with only two abortions. Von Holst[81] removed a myoma weighing two and a half pounds from the uterus at the seventh month of gestation without abortion. Davis of Birmingham, Alabama, reported[82] that a woman three and a half months pregnant was shot in the abdomen. The rifle bullet made twenty-five perforations in her intestines. She was taken eighty-five miles, and then Davis cut out five feet of the intestine. She recovered and gave birth to a living child at term. [79] Cronk, _Oklahoma State Med. Assoc. Jour._, July, 1816. [80] _Amer. Jour. Obstet._, August, 1915. [81] _Upsala Läkareforenings Förhandlingar_, xxi, 8. [82] _Journal Amer. Med. Assoc._, October 28, 1916.