The success of this operation, will, in a great measure, depend not only upon its being undertaken sufficiently early before the patient's strength is exhausted, but upon a sufficient length of time intervening between the removal of the thoracic and abdominal viscera and the extraction of the child. The excellent rule of Dr. Osborn, above quoted, is peculiarly applicable here; for when softened by the effects of incipient decomposition, the body will sometimes even be expelled by the unassisted efforts of the uterus. In a case of this sort, the perforation of the head is the last part of the process to be performed. It will be by all means, desirable not to separate it from the body, but to pass up the curved perforator along the neck, and make an opening behind the ears: this is effected without much difficulty, and the head can be brought away whole, or in portions, according to the nature of the case. PART V. DYSTOCIA, OR ABNORMAL PARTURITION. _Divisions and species._ By the term Dystocia, we understand those labours which either cannot be completed by the natural powers destined for that purpose, or at least, not without injury to the mother or her child.[107] These will, therefore, consist of the two following classes:-- 1. Labours that are difficult or impossible to be completed by the natural powers. 2. Labours which are rendered faulty without obstruction to their progress. The first division of dystocia may either arise from a faulty condition of the expelling powers, or, without any anormality in this respect, it may depend upon the faulty condition either of the child, or of the parts through which it has to pass. As respects the child it may arise from, 1. Malposition. 2. Faulty form and size of the child. 3. Faulty condition of the parts which belong to the child. On the part of the mother this division of dystocia may arise from a faulty condition. 4. Of the pelvis. 5. Of the soft passages. 6. Of the expelling powers. The second condition where labour is rendered dangerous for the mother or her child, without any obstruction to its progress, may arise from, 1. Following too rapid a course. 2. Prolapsus, &c. of the umbilical cord. 3. From accidental circumstances, which render the labour dangerous, viz. convulsion, syncope, dyspnoea, severe and continued vomiting, hæmorrhage, &c. We propose to consider the different species of dystocia in the order above enumerated. CHAPTER I. FIRST SPECIES OF DYSTOCIA.