_Causes._ A large proportion of cases where the uterus gives way during labour, are connected with more or less deformity of the pelvis, and where, from previous severe and difficult labours, its structure has been injured, and rendered incapable of bearing that degree of tension, which even the ordinary exertions of the uterine fibres would require. In many others, the impediment produced by the contracted pelvis, or malposition of the child, has roused the uterus to those violent efforts which have produced the laceration. Organic diseases of the uterus, or cicatrisations of the soft passages from extensive injuries in former labours, either render its powers of resistance defective, or, by increasing the resistance, excite it to unusual violence. "The operation of turning is not unfrequently a cause of laceration of the vagina or mouth of the uterus, _particularly_, where it is performed previous to the soft parts being sufficiently dilated to admit the easy passage of the hand, or where great haste is employed. The same consequences may ensue from rash or violent attempts to remove a retained placenta. I have also known the mouth of the womb to be torn by the imprudent use of the forceps when not sufficiently dilated." (Dr. Collins, _op. cit._ p. 242.) "The sex of the infant, it would appear, may also have some share in occasioning this very distressing occurrence." (_Practical Remarks on Lacerations of the Uterus and Vagina_, by Thomas M'Keever, M. D., p. 4.) Thus, of 20 cases reported by Dr. M'Keever, 15 were delivered of boys and 5 of girls; of the 34 cases described by Dr. Collins, "23 of the children were males. This is satisfactorily accounted for by the greater size of the male head, as proved by accurate measurement made by Dr. Joseph Clarke."