PLACENTA. 379- 



this is a point concerning which there has been a great deal 

 of discussion. 



In injected specimens of the placenta, when an attempt 

 has been made to fill the maternal as well as the foetal ves- 

 sels, the material injected into the uterine vessels has some- 

 times passed through the entire thickness of the placenta and 

 appeared just beneath the transparent chorion at the foetal 

 surface of the organ. This appearance, however, has been 

 thought by some writers to be due to extravasation ; and 

 many physiologists are of the opinion that the placenta has 

 no maternal portion, that it is entirely a foetal organ, and 

 that the maternal vessels do not pass beyond the surface by 

 which it is attached to the walls of the uterus. This opinion 

 we believe to be erroneous ; and we quote in full the follow- 

 ing observation made by John Hunter, who was the first to 

 give a correct idea of the relations between the maternal and 

 the foetal vessels : l 



" The late indefatigable Dr. McKenzie, about the month 

 of May 1754, when assistant to Dr. Smellie, having pro- 

 cured the body of a pregnant woman, who died undelivered 

 at the full term, had injected both the veins and arteries with 

 peculiar success ; the veins being filled with yellow, the arte- 

 ries with red. 



" Having opened the abdomen, and exposed the uterus, 

 he made an incision into the fore part, quite through its sub- 

 stance, and came to what seemed to be an irregular mass of 

 injected matter. The appearance being new, he proceeded 

 no further, and greatly obliged me, by desiring my attend- 

 ance to examine parts, in which the appearances were so un- 

 common. The examination was made in his presence, and 

 in the presence of several other gentlemen, whose names I 

 have now forgotten ; but I have reason to believe that some 

 are settled in this country, who I hope will have an opportu- 

 nity of perusing this publication. 



1 JOHN HUNTER, On the Structure of the Placenta. Observations on certain 

 Parts of the Animal (Economy, London, 1792, p. 163. 



