280 PROFESSOR TURNER ON THE 
branches of the umbilical vein from each other, where it terminated in a pointed 
cul-de-sac. 
The inner or feetal face of the placenta possessed a convoluted appearance, 
with intermediate depressions or sulci, which may be called the primary fissures, 
and the placental substance was continuous across the bottom of each sulcus 
from one convolution to the other. The convolutions ran parallel to each other 
from the narrower to the broader part of the placenta, and were most strongly 
marked in its median portion. When a vertical section was made through the 
placenta and adjacent part of the uterine wall, and the placenta gently drawn 
away from the uterus, its uterine face was also seen to be convoluted, with the 
convolutions and sulci in reverse order to those seen on its chorionic aspect. 
A well-defined layer of mucous membrane, which, from its position, represented 
the serotina, intervened between the muscular coat of the uterus and the 
placenta, and followed closely the windings of the convolutions, dipping down 
into the primary fissures in the form of broad lamine, just as the pia mater dips 
between the convolutions of the cerebrum. Each convolution was split up 
into elongated plates by secondary fissures, into which processes of the mucosa, 
derived not only from the broad laminz just referred to, but from that in 
contact with the uterine face of the convolutions, penetrated (figs. 4,9). Each 
plate was again subdivided by tertiary fissures into small polygonal lobules, 
into which more delicate processes of the mucosa entered, and these could be 
traced through the thickness of the placenta up to the chorion. 
The mucosa could readily be peeled off the uterine face of the placenta, and 
when this was done the laminz were drawn out of the primary fissures, just as 
one can draw the pia mater out of the cerebral sulci when the grey matter on 
the surface of the cerebrum is exposed. The more delicate processes, how- 
ever, which entered the secondary and tertiary fissures were torn through in 
the act of peeling, and remained in the substance of the placenta entangled 
between the foetal villi. When these processes were seized with a pair of fine 
forceps, and gentle traction employed, they could be withdrawn without much 
difficulty from the substance of the placenta. From the ease with which the 
processes lying in the secondary and tertiary fissures tore across in the act of 
peeling off the placenta, there could be little doubt that a similar disruption 
occurs in the separation of the placenta during normal parturition. This 
opinion was confirmed by an examination of the placenta of a Phoca vitulina, 
shed at the full time, which through the kindness of Professor Flower I had 
an opportunity of inspecting in July 1874, in the Museum of the Royal College 
of Surgeons of England.* The part of the mucosa, therefore, which is shed 
* The birth in the Zoological Gardens of the young seal to which this placenta belonged, is re- 
corded by Mr A. D. Barrzert in the Proceedings of the Zoological Society of London, June 11, 1868. In 
his description it is named Phoca fetida, but I believe that the species was vitulina, as stated in the text. 

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