250 PHYSIOLOGY CHAP. 



We shall add a few words on the ligature of the umbilical cord, 

 which must be attended to after the expulsion of the foetus, and 

 the so-called after-birth, the placenta and the decidua. 



If we examine the cord immediately after the expulsion of the 

 child, we find that the arteries are still pulsating and the umbilical 

 vein is turgid with blood. The vein becomes empty about five 

 minutes later and the arteries cease to pulsate in about ten 

 minutes. During this time, therefore, a considerable quantity of 

 placental and umbilical blood reaches the infant, this blood being 

 squeezed out from the uterine walls and the whole of the canal 

 which retracts after delivery and presses the blood out of the 

 placenta, as out of a sponge saturated with liquid. If the infant 

 be placed in a balance immediately after expulsion, it will be 

 found that this blood varies in quantity from 50 to 100 grms., 

 that is to say, it is about a quarter or a third of the blood which 

 circulates in the new-born infant. The child would lose this 

 considerable amount of blood were the cord tied immediately after 

 birth, as is done by many ignorant rnidwives, or those of the old 

 school, instead of the necessary time being allowed for the 

 umbilical vein to become empty. 



After the expulsion of the child, the uterus contracts, causing 

 the gradual detachment of the placenta and the decidua. In order 

 to further this detachment, it is advisable, as recommended by 

 Crede in 1854-61, to press on the uterus with the hand from with- 

 out, so as to stimulate it and increase the pressure during contraction 

 and thus bring about the expulsion of the after-birth or secundines. 



This expulsion takes place from half to three-quarters of an 

 hour after the birth of the child. The placenta and the mem- 

 branes are expelled into the vagina and towards the vulva by the 

 contraction of the uterus and the pressure of the hand of the 

 obstetrician, so that a slight pull on the umbilical cord will 

 complete the expulsion. 



During the passage of the secundines it is advisable to twist 

 into a strand the membranes which have not been expelled, so 

 as to lessen the risk of their being torn and partially retained 

 in the uterus (Fig. 108). 



VI. After the expulsion of the child and the after-birth, the 

 so-called period of puerperium begins, during which the generative 

 apparatus of the woman returns to its pristine state, some slight 

 but indelible internal and external marks of maternity remaining, 

 however. 



The puerperium lasts from six to eight weeks. The phenomena 

 of puerperal involution take place mainly in the uterus. If we 

 look at the genital canal of a woman who has recently been 

 delivered (Fig. 109), we see that the uterus is represented by a 

 voluminous flattened muscular mass, with walls 3-5 cms. thick, 

 enclosing a small cavity filled with a clot of blood. At the point 



