In passing the os uteri the same precautions must be observed, particularly when the os uteri is not fully dilated; at the same time we must fix the uterus itself with the other hand, and rather press the fundus downwards against the hand which is now advancing through the os uteri. In every case of turning we should bear in mind the necessity of duly supporting the uterus with the other hand; for we thus not only enable the hand to pass the os uteri with greater ease, but we prevent in great measure the liability there must be to laceration of the vagina from the uterus, in all cases where the turning is at all difficult. "In those cases (says Professor Naegelé) where artificial dilatation of the os uteri is required to let the hand pass, it should be done in the following manner:--during an interval of the pains, we introduce, according to the degree of dilatation, first two, then three, and lastly four fingers; and by gently turning them and gradually expanding them we endeavour to dilate it sufficiently to let the hand pass. This must only be done under circumstances of absolute necessity and always with the greatest caution--in fact, only in those cases where the danger consequent upon artificial dilatation of the os uteri is evidently less than that, to avert, which we are compelled to turn before it is sufficiently yielding or dilated." (_Lehrbuch der Geburtshülfe_, p. 212. 3tte ausgabe.) This observation from so high an authority evidently applies to those cases where the os uteri is not only soft and yielding, but also nearly dilated; the _forcible_ dilatation of the os uteri is justly deprecated by Madame la Chapelle: "I never attempt to produce this forced dilatation, _not even in cases of hæmorrhage_. But we may frequently promote the dilatation of the passages in a remarkable manner by moistening and relaxing them and diminishing their state of excitement, viz. by the steams of hot water, tepid injections, and more particularly by warm baths and bleeding." (p. 49.) Her diagnosis of the condition in which the os uteri will yield to the introduction of the hand is well worthy of attention. "If the inactive uterus be unable to expel the child, or to make the head clear its orifice although considerably dilated, if, in this state of affairs, the membranes give way, we can feel the os uteri retract, from being no longer pressed upon. How different is this state of passive contraction to the rigidity of an orifice which has not yet been dilated: in this case, although the os uteri is contracted and even thick, it is soft, supple, and easily dilatable; there is no feeling of tightness or resistance; it is little else than a membranous sac, and the head has not descended sufficiently to press upon it; or if the head does not present, it is some part of the child, as for instance the shoulder, which is unable to advance and act upon the os uteri: in this case operate without fear--in the other wait." (_Pratique des Accouchemens_, p. 86.)