OF THE FOETUS. 339 



this reafon, that, in fome women, the menfes 

 are not entirely lupprciTed during the firfl two 

 or three months after conception. I imagine, 

 therefore, that this periodic revolution happens 

 as regularly after a woman has conceived as be- 

 fore, but that the blood is prevented from flow- 

 ing, becaulc the excretories of the uterus are 

 fwelled and fhut up, unlefs when it arrives in 

 fuch large quantities, and ads with fuch forccj 

 as to overcome the refinance with which it is 

 oppofed. In this cafe, a great quantity of blood 

 rulhes out, and an abortion is the confequence. 

 But it frequently happens, that a fmall quantity 

 of blood appears, without producing this effedt ; 

 becaufe the blood has only been able to open a 

 few of the canals or excretories of the uterusj 

 while the reft remain entirely obftruded. 



Though no blood appears, which is generally 

 the cafe, the firft revolution fails not to be ac- 

 companied with the fame painful fymptoms; 

 During the firft fupprcffion of the menfes^ 

 therefore, the uterus is affeded with a confide- 

 rable agitation, which, when a little augmented^ 

 entirely deftroys the produd of generation. 

 Hence we may reafonably conclude, that few 

 of thofe conceptions, which happen a fhort time 

 before the accuftomed return of the menfes, are 

 fucccfsful ; becaufe the adion of the menftrual 

 blood eafily deftroys the feeble roots of a germ 

 i'o tender and fo delicate. Hiofe conceptions^ 

 on the contrary, which take place immediately 



Y 2 after 



