Chap. 42.] Situation oftheFcrtus, 6?r. 407 



is caft off after delivery j _ the portion which covers 

 the ovum, decidua reflexa, becaufe it is reflected from 

 the uterus upon the ovum. The membrana decidua 

 is, according to Mr. Hunter, perforated with three 

 foramina, viz, two fmall foramina, correfponding to 

 the openings of the Fallopian tubes at the fundus uteri, 

 and a larger one oppofite its cervix. The decidua 

 reflexa becomes more thick and vafcular as it ap- 

 proaches the placenta, and conftitutes its maternal 

 part. 



The foetus appears floating in a tranfparent fluid 

 contained in the amhion, fufpended by the umbilical 

 cord, and the head, being the largeft part, and the in- 

 fertion of the umbilical cord being at a confiderable 

 diltance fron\ it, falls loweftj a circumftance very ne- 

 cefTary to fafe &nd eafy delivery. The foetus, when it 

 has nearly obtained its growth, is curled up in an oval 

 form j its back is round, and turned towards one fide 

 of the mother, making that fide more protuberant; its 

 chin is prerTed againft its bread; with its arms it em- 

 braces its knees, and its heels are clofe to its buttocks. 

 A mod curious but fomewhat complicated branch of 

 the animal oeconomy, is the means which nature em- 

 ploys for carrying on the nourifhment of the foetus. I 

 have already mentioned the umbilical cord, which con- 

 nects the foetus to the uterus. One end of this cord 

 is connected to the fubftance called the placenta, and 

 the other enters the navel of the fcetus. The placenta 

 is a fpongy fubftance as broad as the crown of a hat, 

 and about two fingers in thicknefs, and is commonly 

 attached to the upper part of the uterus. The outer 

 furface of the placenta is foft, tender, and fpongy, and 

 commonly bloody, on account of its feparation from 

 the y.efiels of the uterus. Its internal furface, where 

 it is covered by the membranes, is firm, glofly, and 

 D d 4 beautifully 



