PROFESSOR W. TURNER ON THE PLACENTATION OF THE APES. 
539 
almost complete, but a specimen where they are completely separated. The 
umbilical vessels are directed to the edge of one of the lobes, but just before reaching 
it they give off branches which pass to the other lobe. Hecker and J. Matthews 
Duncan t have also referred to cases of bilobed human placentas. In my specimen 
of Macacus, in the one figured by John Hunter, and in several of the placentae 
figured by Breschet, the division into lobelets by furrows on the surface of the 
organ was also distinct. 
The mucous lining of the non-placental part of the uterine cavity of Macacus 
obviously corresponded generally with the decidua vera of the human gravid uterus ; 
but it differed from it in several points of structural detail. From the intimate 
adhesion which subsisted between the chorion and mucosa in the Macacus it was not 
easy to make a complete separation between the two surfaces, but when this was 
effected, the fine ridges and furrows described in a previous section of this memoir 
(p. 530) were observed. 
In the human uterus the chorion and the free surface of the decidua are not so 
intimately adherent to each other as in the Macacus, although, as has been pointed 
out by various observers, at least in the later months of pregnancy adhesions do occur. 
I have seen in a human uterus at the fifth month the free surface of the decidua vera 
finely corrugated into numerous delicate convoluted folds, whilst thread-like prolonga- 
tions of the chorion, apparently atrophied villi, were adherent to this surface. In 
another specimen, at the seventh month the outer surface of the chorion was closely 
adherent to the decidua lining the uterine cavity. When the chorion was stripped 
off, a well marked layer of decidua, the decidua reflexa, was attached to it, and a 
somewhat thicker layer remained on the uterine wall. To separate these from each 
other, flakes and threads of decidual tissue had to be torn through ; but as the 
separation was not made precisely in the same plane throughout, it was clear that 
the decidua vera and reflexa had become blended together. After the separation 
had been made, the free surface of the vera was seen to be furrowed, and to these 
furrows ridges of the chorion were closely adapted. In a human uterus in the ninth 
month, whilst the chorion, with the decidua reflexa, was generally adherent over the 
whole extent of its outer surface to the vera, a smaller amount of traction was 
sufficient to draw them asunder. When the chorion and reflexa were removed, the 
surface of the vera was smooth and not corrugated. 
Observations are wanting on the appearance of the decidua vera in the early stages 
of gestation in the monkey, but in the human female as early as the twelfth or 
thirteenth days of gestation Reichert’s observations have shown J that the free 
surface of this decidua was divided by furrows into “ islands ” which had an irregular 
* ‘ Klinik der Geburtskunde.’ Band II. 
t ‘ Mechanism of Natural and Moi’bid Parturition,’ Note, p. 313. Edinburgh, 1875. 
+ ‘ Bescbi’eibung liber friihzeitigen Mensclilichen Fruclit. Abhand. der Konig. Akad. der Wissenscbaft.’ 
Berlin, 1873. 
