Any investigations which throw light on the causation or treatment of that greatest of obstetrical calamities, rupture of the uterus, are of importance to the obstetrician, the surgeon and the general practitioner. The most frequent causes of this condition are obstructions to the descent of the fetus, with neglect of the procedures necessary for delivery of the child, as in patients treated by midwives or by the laity. Such obstructions are often in the form of contracted pelves, or tumors of the pelvis encroaching on the parturient canal. A normal fetal head of large measurements or a hydrocephalic head may cause obstruction by failure to enter a normal pelvis. Malpositions of the fetus, as a transverse position with a shoulder presentation, lead invariably to obstruction unless properly cared for. Rupture of the uterus has been the direct result of manipulations, as attempted versions or the use of the hand or