PROFESSOR W. TURNER ON THE PLACENTATION OF THE APES. 
557 
is prolonged into the interior of the placenta, as the injection of the organ interfered 
with the use of the nitrate of silver reaction. I could not in this specimen obtain 
any evidence of a layer on the villi external to their cellular covering, but I may refer 
to a previous observation* on the structure of the villi in the placenta of the 
M. ncmestrinus in the Oxford Museum, in which a layer of apparently flattened cells 
seemed to be situated external to the proper cellular covering of the villus. But 
whether an endothelial prolongation of the lining of the maternal vessels be present or 
not within the placenta, there can I think be no doubt that the inter- villous spaces in 
Macacus are of the same nature as the corresponding spaces in the human placenta. 
Should, as is most probable, the cellular covering of the villi be derived from the 
decidua, then in the human placenta and in the Macacus, as in the other placental 
mammals, a layer of cells, derived from the epithelium of the uterine mucous mem- 
brane, would be interposed between the maternal blood and the capillary terminations 
of the foetal vessels. 
The stage of development of the placenta in the Macacus was too advanced to 
enable me to determine if the villi of the chorion had had any relation to the 
utricular glands. 
The comparison that I have now made between the gravid uterus and placenta in 
Macacus cynomolgus and the human female proves that they correspond in the form of 
the uterus and in the arrangement of the foetal membranes, and that they both possess 
a discoid placenta, which in the Macacus is divided into two lobes, but is undivided 
in the human placenta. In the arrangement and relative position of the constituent 
parts of the placenta they also correspond, and although some differences of detail in 
the characters of some of the structures occur, yet in the main features of construction, 
makroscopic as well as microscopic, they have a close resemblance to each other. 
I have little doubt, if a detailed examination of the placenta in the other genera of 
Apes were made, that a similar resemblance in structure would be found. 
Explanation of Plates. 
PLATE 48. 
Fig. 1. A view of the interior of the gravid uterus of Macacus cynomolgus, obtained 
by making a longitudinal incision through the anterior wall. The foetus 
is shown undisturbed in its position. 
v. Vagina. 
c. Cervix uteri. About one-third less than nature. (Page 527.) 
* Cited in the Memoir “ On the Placentation of the Sloths, ” p. 97. 
