The theory at one time so universally entertained, that the obliquity of the uterus was the chief cause of malposition of the child, has long since been disproved, although it continues to find a few adherents to the present day: the uterus, in fact, towards the end of pregnancy, is scarcely ever quite straight; the upright posture of the human female rendering it almost necessary that the fundus should incline somewhat to one side or to the other, or forwards, and yet we find that it has no influence upon the position of the child when labour comes on. The moment a pain commences, the fundus moves towards the median line of the body, so that its axis corresponds nearly with that of the pelvic brim: as the pain goes off, so does it return towards its former oblique position. Even in those cases where it is strongly inclined forwards, and where the abdomen is quite pendulous, the position of the child is unaffected by it. Where, however, the uterus has been altered in point of form, where from irregular contractions of its fibres it has been pulled down unequally to one side, while it is quite relaxed in the opposite direction, the position of the child may be seriously affected, for it will now present obliquely as regards its long axis, and become a case of malposition. We may, therefore, state that the causes of arm or shoulder presentations are of two kinds, viz. where the uterus has been distended by an unusual quantity of liquor amnii; or where, from a faulty condition of the early pains of labour, its form has been altered, and with it the position of the child. It is a well-known fact that cross births, as they have been called, are frequently preceded by severe spasmodic pains in the abdomen, from which the patient suffers for some days or even weeks before labour has commenced: the uterus is more or less the seat of these attacks, which usually come on towards night-time; and, in some instances, it is felt for the time hard and uneven from irregular contraction. It was the circumstance of this symptom having preceded five successive labours of a patient, in all of which the child had presented with the arm or shoulder, which induced Professor Naegelé, when attending her in her sixth pregnancy, to endeavour to allay these cramp-like pains, which had begun to show themselves as severely as on former occasions. Having tried opium by itself, and also in combination with ipecacuanha or valerian without effect, he ordered her a starch injection with twelve drops of Tinct. Opii every night as long as she continued to suffer from these attacks: the spasms soon ceased, nor did they appear again during the remainder of her pregnancy, and he had the satisfaction of delivering her at the proper time of a living child, which presented in the natural manner.