=Diseases of the Membranes.=—_Hydramnios_, or polyhydramnios, is the name applied to the condition where an excess of liquor amnii is formed. The amount normally present varies, but anything in excess of four pints could be called hydramnios. Six gallons have been reported. Since the source of the liquor amnii is not positively known, the etiology of hydramnios must be equally obscure. It is occasionally associated with morbid conditions of the mother, such as hepatic or cardiac dropsy, but more frequently with developmental anomalies of the fœtus. Since the mother is usually healthy and the fœtus frequently deformed, the theory is advanced that the disease is fœtal in origin. It frequently occurs with twin pregnancies, and in the first months it is most plausible that the liquor amnii is in some way derived from the fœtus. The disease is more common in multiparas. It is generally slow in onset, but it may be acute, and an immense amount of fluid may be formed in a few weeks. _The symptoms_ are those due to pressure from the extremely large uterus. _The treatment_, if interference with heart or lungs becomes pronounced, is puncture of the membranes. The child need not be considered for it is usually dead or deformed. _Oligohydramnios_ is the condition where the liquor amnii is deficient in amount. It gives no maternal symptoms, but it is the cause of many birthmarks and fœtal deformities (club-foot, spinal curvature, wry-neck, ankylosis of joints). Amniotic adhesions are usually associated with oligohydranmios and cause deformities by amputation of limbs, strangulation of cord, and production of six fingers. =The placenta= may show anomalies of size and shape. Thus, there may be two lobes, or three. There may be the main placenta and a small out-lying mass connected by membrane and vessels with the larger segment. The cord may be inserted in the middle or at the edge and yellowish-white masses called infarcts may be found in its substance. Unusual size and weight of the placenta are suggestive of syphilis. =Abnormal conditions of the fœtus= may arise from primary or transmitted disease or from errors of development. The developmental errors may be monsters, _hydrocephalus spina bifida_, etc., which may not influence the pregnancy. The most commonly transmitted disease is syphilis, which may produce abortion, premature labor, or a child born with syphilitic skin changes on palms and soles, as well as internally. CHAPTER VI ABNORMAL PREGNANCY (Cont’d) =Extrauterine Pregnancy.=—This is a pregnancy which occurs outside the uterus, and while the event usually happens in the tube, cases have been reported where the egg developed in the ovary or abdomen.