PECULIARITIES OF THE FCETUS. 279 



the mother. The placenta was infiltrated with Prussiate of iron, 

 and considerable quantities of blue plaster were found in the ca- 

 vity of the uterus. 



In the progress of the injection with the Prussiate of iron? into 

 the uterine sinuses, the membranes were raised from the uterus 

 in vesications. 



The parts having been distended arid put aside to dry, at the 

 end of a fortnight they were examined again by incisions, and 

 the same evidence of the want of direct vascular communication 

 was renewed. But the placenta was found to be infiltrated ac- 

 cording to certain rules seeming to depend on its organization. 

 The blue colouring matter on the part of the uterus, and the 

 yellow on the part of the foetus, determined in it two parts, one 

 uterine and the other foetal, closely and alternately interlocked, 

 like a dove-tailing: the uterine processes passed to within a 

 short distance of the free surface of the placenta, while the foetal 

 processes went almost to the base of the placenta. The con- 

 fines of the two colours were defined well by this abrupt ter- 

 mination, the borders of these dove-tails. The appearance 

 would, perhaps, be better designated by the terms uterine lobes, 

 and fetal lobes, alternately penetrating, so as to constitute the 

 whole mass of the placenta. No distinct vessel of a blue co- 

 lour could, however, be seen in the uterine lobes; but a few 

 very sparse yellow ones were visible. On raising up these 

 uterine divisions, the orifices of the uterine sinuses were seen 

 at their base. 



The inference from this experiment is, that though there is no 

 direct connexion of blood vessels between the mother and the 

 foetus, yet there is a part of the placenta which seems to hold a 

 special connexion with the uterine sinuses, and which may pos- 

 sibly, therefore, by interstitial circulation, establish a connexion 

 with the foetus. The facts are at any rate presented as they 

 occurred. 



The effete blood of the umbilical arteries becomes regenerated 

 in the placenta, assumes a brighter hue, and is returned to the 

 foetus by the umbilical vein-. According to the theory of Saba- 

 tier concerning the use of the Eustachian valve, if the latter 

 did not exist, the fresh blood brought to the heart by the 

 ductus venosus, instead of being diverted into the left auricle 

 through the foramen ovale, would be received by the right 



