Double ovariotomy brings on abortion in the early months of pregnancy oftener than in the later, probably from the loss of the corpus luteum, which, it appears, is necessary for the growth of the uterus. Appendicitis and appendectomy are especially likely to interrupt gestation, apparently as a result of infection and because pregnant women are prone to defer operation. The traumatism of criminal abortion, punctures and lacerations from bougies and curettes, and the exhibition of drugs like ergot and cantharides, are sources and results of abortion. Drugs will not empty the uterus unless they are given in poisonous doses which endanger the woman's life. In the father, syphilis, tuberculosis, general paresis, general debility from alcoholism, unchastity, and senility, and septic conditions of the generative tract, may cause abortion. Many men who work with lead, phosphorus, mercury, or X-rays are sterile, and before they become totally sterile their condition appears to cause debility in the fetus which leads to abortion. In paternal lead poisoning there is a reduction of about 20 per cent. in the weight of the infants at birth, and a general weakness and retardation of the child. The children of lead-poisoned fathers are frequently permanently under weight. Coition during gestation is a cause of abortion, and the fault here, as a rule, lies with the husband. St. Thomas[83] said: "St. Jerome protests against the sexual approach of the husband to his gravid wife, not that in this condition such an act is always a mortal sin, unless there is probable danger of abortion." St. Alphonsus[84] says if there is danger of abortion the use of the debitum is a grave sin. In n. 924 he again teaches that while it is true that if by the use of the debitum the life or formation of the fetus is endangered or checked the right to the use of the debitum is, in such circumstances, lost, yet he thinks that in pregnancy there is little danger of abortion from this cause, especially near term. [83] _In. 4, dist. 81._ [84] _Theologia Moralis_, n. 943. Sabetti-Barrett[85] says the wife is excused from the debitum conjugale if the husband is drunk, or if there is a rational dread of grave injury, or grave danger to health. Genicot[86] thinks that in pregnancy it "can scarcely be shown that there is a notable danger of abortion." Lehmkuhl[87] holds that a married person is not obliged to grant the debitum if there is great danger of abortion; but, he adds, "Even then, if there is a grave danger of incontinence I do not think it certain that there is an absolute obligation to abstain." [85] _Theologia Moralis_, n. 936. [86] _Theologiae Moralis Institutiones_, vol. ii, n. 544. [87] _Compendium Theologiae Moralis_, n. 1114.