550 
PROFESSOR W. TURNER ON THE PLACENTATION OF THE APES. 
interior of the cotyledons for a greater or less distance, but not reaching the chorion, 
were also described as secondary or intra-cotyledon ary dissepiments. Since that time 
I have examined the intra-placental prolongations of the decidua in younger placentae. 
In the placenta at the fifth month the arrangement was very instructive. Not only 
did very definite bands of decidua separate the lobes of the placenta from each other, 
but numerous intra-cotyledonary or secondary dissepiments passed into each lobe, both 
from the general surface of the serotina and from the surface of the inter-cotyledonary 
dissepiments. From these secondary dissepiments numerous still more delicate off- 
shoots branched off in the intervals between the villi of the chorion, where they 
formed a network in the interspaces of which the villi were contained. Hence the 
whole interior of the placenta was traversed by prolongations of the decidua serotina, 
which formed an intervillous network of trabeculae. The dissepiments had the 
characteristic structure of the compact layer of the decidua ; but the intervillous off- 
shoots, though they contained the large decidua cells close to where they arose from 
the dissepiments, yet were made up in great part of a delicately fibrillated connective 
tissue in which scattered corpuscles were imbedded. 
Kolliker, in the second edition of his ‘ Entwicklungsgeschichte ’ (p. 336, 1876), has 
recently described these inter-cotyledonary dissepiments by the name of septa placentae, 
and his observations on these bands of decidua closely correspond with those I had 
previously made on the mature placenta. The surface of the decidua, which is 
directed to the interior of the human placenta, is not therefore a plane surface, but 
presents an irregularly uneven appearance from the numerous intra-cotyledonary 
dissepiments which project from it. 
In the Maccicus nemestrinus described by Rolleston, processes of maternal tissue 
were followed into the placenta. In M. cynomolgus the placental surface of the 
decidua serotina was uneven from the numerous hillock-like elevations which in the 
description of the organ (p. 534) I have compared with stalagmites: these correspond 
to the intra-cotyledonary dissepiments of the human placenta. In the Cynomolgus, 
however, though the division into cotyledons is marked by furrows on the chorionic 
surface of the organ, and though there is a special thickening of the decidua opposite 
the borders of contiguous lobelets, yet the decidua does not send prolongations between 
the lobelets up to the surface of the chorion, like the inter-cotyledonary dissepiments 
of the human placenta. Hence the intra-placental maternal blood spaces in Macacus 
form throughout the interior of the organ a more continuous anastomosing cavernous 
arrangement than in the human placenta. 
The presence of the definite arrangement of stratified cells on the placental surface 
of the chorion of M. cynomolgus, which I have named the sub-chorionic cells, is of 
particular interest in connexion with some observations made during the last six years 
on the structure of the human placenta. In 1872 Winkler described and figured 
diagram matically , ” by the name of Schlussplcctte, a layer extending over the entire 
* “ Zur Kenntniss der Mensclilichen Placenta,” ‘ Archiv fur Gynakologie,’ iv., 238. 
