DELIVERY OF THE AFTER-BIRTH. 539 



face of the cake, which is concave, like the bottom of a bottle; 

 sometimes it is effected gradually proceeding from the centre to 

 the circumference, or it may begin on the edge, and if the involucra 

 resist long, the smooth or internal surface may become the outer 

 one, and the blood being confined on the outside of the membranes, 

 does not escape until after the expulsion of the after-birth, the size 

 of which it sometimes surprisingly augments. 



At. other times, in detaching itself, the placenta rolls up in the 

 shape of a cylinder or cornet cVouhlie. In that case it presents by 

 its uterine surface or by its edge to the several passages; the blood, 

 not being confined, flows out at the vulva as fast as it is poured into 

 the womb, and commonly ceases to flow as soon as the placenta is 

 delivered. 



Second Stage. When once detached, the placenta presses upon 

 the OS uteri, engages in the orifice, which it irritates, and the womb, 

 which is irritated by its presence, becomes more and more con- 

 stricted, contracts, and soon forces it to pass into the vagina. When 

 there, it soon gives rise to a sensation of uneasiness, tenesmus, or 

 bearing down, which still solicit the contractions of the womb, and 

 bring into play the eflforts of the abdominal muscles. The diaphragm 

 and muscles of the belly react upon the abdominal viscera and 

 womb, as if for the expulsion of the foetus, and the placenta clears 

 the inferior strait. 



Some persons, and among them M. Desormeaux, divide this pe- 

 riod of expulsion into two stages. It is true, that in order to pass 

 from the womb into the vagina, the after-birth sometimes requires 

 so considerable a degree of dilatation of the os uteri, that a particular 

 stage might be made of it, and that it may afterwards remain so 

 long in the passage that its entire expulsion really constitutes a dis- 

 tinct period; but as these two stages are far from being always so 

 distinctly marked, it appears to me that they may without inconve- 

 nience be confounded together. However, this is an affair of choice, 

 not of necessity. 



If the labor have been a long one, if the woman be strong, if the 

 means of art have been applied for the extraction of the child, and if 

 the womb be in a state of considerable energy, the placenta falls into 

 the vagina and presents itself at the vulva almost immediately after 

 the delivery of the child. In opposite cases, the delivery of the 

 placenta does not take place for half an hour, and sometimes eveu 

 for several hours. It may also happen, that it shall not take place 

 for a whole day, or even for several days. This difl!erence is easily 

 explained: in the first case, the ovum which has been long detached 

 descends whole, along with the foetus. The womb, contracting 



