374 MINOT. [ Vou. te 
Many parts of the vessels are filled with coagulum, suggesting 
thrombi formed during life, as has been asserted to occur nor- 
mally in the human placenta. For the most part, the vessels 
contain normal blood, save that there is an excess of leucocytes ; 
in some vessels, however, there are large clear refringent bodies 
which look like vesicles. What these bodies are I am unable 
to say — possibly they come from breaking down of the endo- 
thelium. The multinucleate cells, Fig. 14, are large and very 
much crowded ; they contain each a dozen nuclei, more or less. 
I have nothing of importance to add to the previous descriptions. 
In the outer zone we notice at once that the expansion of the 
blood-vessels is far less active near the muscularis than further 
in; indeed, we might subdivide the zone into an outer compact 
and an inner cavernous layer. The vascular epithelium is far 
degenerated, Fig. 16; A is a surface view; B and C vertical 
sections; each cell forms a more or less independent projection ; 
the cells vary extremely in size; the nuclei are either single or 
multiple; in the former case they may be small and compara- 
tively regular, or large and very irregular in shape; in the latter 
case they are of unequal sizes. The perivascular cells are in- 
numerable; their appearance is indicated by Fig. 15; but where 
the blood-vessels are wider, or, in other words, towards the glan- 
dular zone, they exhibit signs of breaking down; the signs in 
question are indistinctness of outline, granular appearance of 
the protoplasm, and the difficulty of staining the nuclei. As 
the changes are slight, they are perhaps accidental. It must be 
left for future examination of later stages to show whether they 
do break down or not. I also think that there is a tendency for 
the multinucleate cells to invade the territory of their uninu- 
cleate neighbors. 
The peri-placenta agrees with the outer zone of the placenta 
in its parenchymal structure, except as to two points: I°, it is 
now invaded to a slight extent by the multinucleate cells, at 
the spot nearest the placental glands; I have no reason to sup- 
pose that these cells actually migrate into the peri-placenta, but 
presume that they arise zz sztz,; 2°, near the ob-placenta there 
are in some parts young monster cells lying close under the 
epithelium ; the evidence is better here than anywhere else I 
have observed that the monster cells arise from the epithelium. 
The ob-placenta now has monster cells throughout almost its 
