vi PKEGNANCY PAETUKITION PUEKPEKIUM 251 



of transition between the body and neck of the uterus at the 

 level of the internal orifice, the thickness of the walls suddenly 

 diminishes, and the whole cervical canal looks like a large sac 

 falling into numerous folds. This cavity of the cervix is bounded 

 above by a constriction called the ring of contraction ; it is more 

 open below and the lips of the mouth of the uterus descend into 

 the vagina in the form of a fleshy intumescence. The vagina 

 takes the form of a sac with many folds and walls sloping down 

 towards the vulva. Owing to the great stretching of these walls, 

 the uterus can easily be made, from above downwards, to sink 



FIG. 108. Twisting^the membranes into a cord. (Bumm.) 



in the pelvis by pressure of the hand on the abdomen, so that 

 the " mouth of the uterus " may be seen at the vulvar orifice. 



This state of things very soon begins to change gradually, 

 as the tissues recover their tone and original consistence. The 

 vulva contracts first, then the vagina, and in eight days they regain 

 their normal tone. On the tenth day the tip of the finger can 

 no longer penetrate the cervical canal. The external orifice only 

 closes in the third week and assumes the appearance of a trans- 

 verse fissure, a permanent mark of parturition. 



The body of the uterus undergoes, during the puerperium, a 

 marked process of involution owing to fatty degeneration of the 

 muscular fibres which hypertrophied during pregnancy. This 

 degeneration is the result of anaemia caused, during parturition 



