342 OF THE GROWTH, &c. 



.V 



ftrength, will be born at the tenth revolution, 

 which is the moft ufaal term. But, when the 

 foetus acquires not this degree of ftrength and 

 perfection in nine months, it will remain in the 

 uterus till the eleventh, or even the twelfth revo- 

 lution, that is, till the tenth or eleventh month : 

 Of fuch late births many examples are record- 

 ed. 



Other reafons, to confirm the opinion, that 

 the menflrual flux is the occafional caufe of 

 births at different periods, may be produced. 

 The females of all animals which have no men- 

 fes bring forth very nearly at the fame terms : 

 The diiierence in the times of geftation is ex- 

 tremely fmall. We may, therefore, conclude, 

 that this variation, Vv^hich is very great in wo- 

 men, proceeds from the ad;ion of the menftrual 

 blood, which is exerted at every periodic revo- 

 lution. 



We have already remarked, that the placenta 

 adheres to the uterus by the papillae only ; that 

 there is no blood either in thefe papillae, or in 

 the lacunae in which they are inferted; and that, 

 when they arc feparated, an operation which 

 requires no great effort, a milky liquor only if- 

 fues from them. Why, therefore, is the birth 

 of a child uniformly followed by a confiderable 

 haemorrhage, fir ft of pure blood, and afterwards 

 pf bipod mixed with a vv^atery fluid? This blood 

 proceeds not from the feparation of the placen- 

 ta- for the papillae are drawn out of the lacunae 



without 



