If the membranes be not yet ruptured we should use the greatest caution to preserve them uninjured: the hand must be gently insinuated between them and the uterus, and should be passed either until the feet are felt, or at least, until it has gained the upper half of the uterus. Now, and not till now, ought they to be ruptured. As this is done at the side of the uterus little or no liquor amnii escapes, for the torn membranes are pressed closely against the uterine parietes, and the vagina is completely closed by the presence of the arm in it acting as a plug; the uterus is unable to contract upon the child on account of the fluid which surrounds it, and the hand, therefore, passes up with great facility. The uterus is not diminished by the loss of its liquor amnii; its contractile power is, therefore, not increased. When the hand has broken the membranes it can move about in perfect freedom: if the feet have not as yet been reached they will now be easily found, and the position of the child will be changed without difficulty. The importance of passing in the hand without rupturing the membranes was first shown by Peu in 1694.[89] But it excited little or no notice at the time, not even by La Motte, who paid so much attention to improving the operation of turning. Dr. Smellie appears to have been the first after Peu who recommended this mode of practice, although he makes no mention of his name. "Then introducing one hand into the vagina we insinuate it in a flattened form within the os internum, and push up between the membranes and the uterus as far as the middle of the womb: having thus obtained admission, we break the membranes by grasping and squeezing them with our fingers, slide our hand within them without moving the arm lower down, then turn and deliver as formerly directed." (_Treatise on the Theory and Practice of Midwifery_, vol. i. p. 327. 4th edit.) In 1770, Deleurye again pointed out the value of this mode of introducing the hand, and expressly directs us "introduire la main dans la matrice _sans_ percer la poche des eaux, détacher les membranes des parois de ce viscère, et les percer à l'endroit où l'on juge que les pieds peuvent le plus naturellement se trouver."[90] Dr. Hamilton, of Edinburgh, five years afterwards recommended the same method, and in nearly the same terms. Little notice, however, has been taken of it since, either in this country or upon the Continent, and the old objectionable mode of rupturing the membranes at the os uteri is still taught even by the most modern authors. The celebrated Boer also added his testimony in favour of Deleurye's mode of practice,[91] and it has still farther been confirmed by Professor Naegelé.