THE PLACENTA. 627 



It is very easy to demonstrate the arrangement of the foetal 

 tufts in the human placenta. They can be readily seen by the 

 naked eye, and rnay be easily traced from their attachment at the 

 under surface of the chorion to their termination near the uterine 

 surface of the placenta. The anatomical disposition of the pla- 

 cental sinuses, however, is much more difficult of examination. 

 During life, and while the placenta is still attached to the uterus, 

 they are filled, of course, with the blood of the mother, and occupy 

 fully one-half the entire mass of the placenta. But when the pla- 

 centa is detached, the maternal vessels belonging to it are torn off 

 at their necks (Fig. 228, c, c, c, c), and the sinuses, being then 

 emptied of blood by the compression to which the placenta is sub- 

 jected, are apparently obliterated ; and the foetal tufts, falling to- 

 gether and lying in contact with each other, appear to constitute 

 the whole of the placental mass. The existence of the placental 

 sinuses, however, and their true extent, may be satisfactorily de- 

 monstrated in the following manner. 



If we take the uterus of a woman who has died undelivered at 

 the full term or thereabout, and open it in such a way as to avoid 

 wounding the placenta, this organ will be seen remaining attached 

 to the uterine surface, with all its vascular connections complete. 

 Let the foetus now be removed by dividing the umbilical cord, and 

 the uterus, with the placenta attached, placed under water, with its 

 internal surface uppermost. If the end of a blowpipe be now 

 introduced into one of the divided vessels of the uterine walls, and 

 air forced in by gentle insufflation, we can easily inflate, first, the 

 venous sinuses of the uterus itself, and next, the deeper portions 

 of the placenta ; and lastly, the bubbles of air insinuate themselves 

 everywhere between the foetal tufts, and appear in the most super- 

 ficial portions of the placenta, immediately underneath the trans- 

 parent chorion (a, a, Fig. 228); thus showing that the placental 

 sinuses, which freely communicate with the uterine vessels, really 

 occupy the entire thickness of the placenta, and are equally exten- 

 sive with the tufts of the chorion. We have verified this fact in 

 the above manner, on four different occasions, and in the presence 

 of Prof. C. E. Oilman, Prof. Geo. T. Elliot, Dr. Henry B. Sands, 

 Prof. T. G-. Thomas, Dr. T. C. Finnell, and various other medical 

 gentlemen of New York. 



If the placenta be now detached and examined separately, it will 

 be found to present upon its uterine surface a number of openings 

 which are extremely oblique in their position, and which are 



