The foresight of Nature is not limited to the facilitating the motion* 

 on one another, of the osseous parts of the skull of the foetus, and of the 

 pelvis of the motner; her care extends to the soft parts of the latter; 

 these are soaked in mucus, so as to reflux their tissue several days before 

 parturition, and are so disposed, as was already observed (CCI.) that they 

 may, without rupture or violence, and by the mere unfolding of the folds 

 of the skin, yield to a considerable degree. As the placenta and the 

 membranes are not expelled immediately after the foetus, it is customary 

 to separate them, by dividing the umbilical cord, near the navel. It is 

 unnecessary to tie this cord, at the. part near the mother, every communi- 

 cation being intercepted between the placenta and the uterus, so that no 

 blood could flow but that of the placenta. Not so, however, with the 

 part nearest the foetus 5 though the changes which take place in the cir- 

 culation, at the moment when the chest is dilated, and allows the air to 

 distend the pulmonary tissue, divert the blood from the umbilical vessels: 

 these changes, however, in the circulation of the fluids, might come on 

 slowly, from the weakness of the new born child ; hence it is always 

 prudent to prevent, by a ligature, a loss of blood that would increase the 

 debilty., 



The human ovum is very seldom detached entire, and never so without 

 considerable danger; that is, the foetus is not expelled with its -mem- 

 branes and in the liquor amnii, for .these are not, in general, expelled till 

 a quarter of an hour, half an hour, or even a full hour after the delivery 

 of the foetus. When the uterus is completely emptied, its cavity be- 

 comes obliterated by the approximation of its sides ; this organ, con- 

 tracted on itself, sinks behind the pubis, its cervix closes, and this even 

 impedes the delivery of the after-birth, when the latter is protracted too 

 long. The parietes of the uterus, imbued with fluids, are thicker than 

 in their natural condition ; but they decrease in size, in consequence of 

 the lochial discharge, and return to their wonted thickness. 



When labour is over, the uterus falls as it were, asleep, and enjoys 

 repose, after painful exertion. The humours cease to be determined to 

 that organ, towards which they are no longer directed, by any irritation, 

 and they flow towards the mammary glands, to supply the secretion of 

 the fluid which is to nourish the new born child. 



CCXVIII. Of twins. Though, in the human subject, the offspring 

 is generally single it is not uncommon for a woman to bring forth two 

 children at once; it has even been calculated, that the proportion of twin 

 cases to single births, was one to eighty. Indeed, there are cases of 

 women who have brought three children at a birth. Haller calculates 

 that the number of these last, to those of single births is as one to seven 

 thousand. The cases of four children at a birth, are still less frequent, 

 and if three children born at once, seldom live long, the others, which, 

 when born, are at the size of children at five months, cannot live. Only 

 one or two instances are known of five children, having been born at a 

 birth ; Haller, therefore, is guilty of exaggeration, in saying that these 

 cases are to the ordinary cases, in the proportion of one to a million. I 

 take no notice of the instances in which a greater number are said to have 

 been delivered at once, because those cases are not well authenticated. 

 In the case of twins, each child has its own umbilical cord terminating, 

 sometimes, in a separate, and sometimes in a single placenta. Both foe- 

 tuses are enveloped in one chorion, but each has a distinct amnion, and 

 floats in a separate liquor amnii. It would be curious to know, whether 



