PROFESSOR W. TURNER ON THE PLACENTATION OF THE APES. 
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imbedded for some distance in the hillock, and at times even extended close up to its 
base of origin (fig. 11). The extent to which the villus penetrated into the substance 
of the hillock was recognised, not only by its structural difference from the decidua, 
but by the passage of the branches of the umbilical vessels, filled with a blue injection 
and surrounded by the proper tissue of the villus, for a greater or less distance down 
the axis of the hillock. As the villus emerged from the apex of a hillock the strata of 
decidua cells which invested it diminished both in number and thickness, so that at a 
short distance from the hillock the cellular covering of the villus was reduced to the 
single layer of cells investing the placental villi. 
Slender bands and thin membrane-like flakes were occasionally to be seen passing 
between and connecting together the free ends of the bud-like offshoots of the villi. 
These bands and flakes were continuous with the cellular investment of the villi. 
Sometimes a slender band, terminating in a pointed end, extended for a short distance 
from a bud, and apparently had been a connecting band which had been torn in two. 
These bands and flakes were most probably derived from the decidua. 
The thick layer of the decidua serotina which remained attached to the wall of the 
uterus on stripping off the placenta presented a peculiar and very characteristic 
spongy or honey-combed appearance, owing to the numerous areolae or loculi which 
it contained (fig. 5). The cavities of these loculi varied in size, some being so small as 
only to be capable of containing a small shot, whilst others could hold a common pea. 
The loculi were imperfectly separated from each other by thin semi-translucent septa, 
and the cavities of adjacent loculi freely communicated through gaps in the septa, 
bounded by a well defined and often falciform edge. The free surfaces of the septa 
were quite smooth. 
When examined microscopically the walls of the loculi were seen to consist of a 
layer of cells on the free surface, and of a subjacent vascular connective tissue. The 
cells on the free surface had an epithelial-like arrangement, but they varied materially 
both in shape and size. The largest of the cells were as big as, or even larger 
than, the more superficial cells of the tessellated epithelial lining of the mouth, whilst 
others were not more than one-third or one-fourth that size (fig. 9). They were 
fitted together by then- edges so as to form a continuous pavement. They had 
not, however, the irregular polygonal form of an ordinary squamous epithelium. The 
larger cells were often rounded along a part of the edge and indented, or with short 
processes at other parts ; their protoplasm was very pellucid or faintly granulated, 
and the nuclei were of large size, often rounded in form, and so granulated that 
the nucleolus was usually obscured. Many of the smaller cells were flask -shaped 
or fusiform, with pellucid protoplasm and granulated elongated nuclei. At and near 
the falciform openings in the septa the cells were very much smaller than on the 
plane surface of a septum ; in many cases they were not so large as the nuclei of the 
larger cells. Their shape was polygonal, their nuclei rounded or egg-shaped, and in 
many cases the nucleus was enveloped by only a thin layer of protoplasm. These 
MDCCCLXXVIir. 3 z 
