RELATION OF VESICULAR MOLE TO CHORION CARCINOMA 155 
surface of this, are seen the remains of villi, most of which have lost their epithelium, 
the myxomatous core being all that is left. Close to, but separated by the above- 
mentioned semi-organized blood clot, are masses of granular protoplasm, containing 
a number of oval nuclei. These are deeply stained and shew great variety in their 
size and shapes. They are seen penetrating into the muscular coat, at times, as a 
long strand making its way inwards towards the blood spaces by which the muscular 
wall is intersected ; at others, breaking off into small buds or even isolated cells. 
These wandering cells appear to possess great powers of penetration, as they are met 
with in all parts of the section. They stain deeply, and so stand out prominently 
from the rest of the tissue, the nuclei being especially rich in chromatin. 
About midway between the mucous and serous coats two hydatidiform vesi- 
cles are seen, surrounded in the greater part of their extent by a haemorrhagic area. 
The stroma of the vesicle is composed of myxomatous tissue, towards the centre it is 
becoming thinned, and spaces are seen which probably during life were filled with fluid. 
There is no sign of any overgrowth in the stroma, and it does not penetrate at any 
point the investing epithelial layers. It is to these latter that the special interest 
of the section attaches (see Figs. 12 and 13, Plate XII). 
The epithelium is present, covering the entire surface of the vesicle. Both 
syncytium and Langhans' zellschicht are well seen, and both are in a state of active 
proliferation. The cells lying in immediate contact with the stroma are almost cubical 
in shape, though in places much irregularity exists, and they are arranged in rows, 
sometimes as many as six layers deep. Next to these, and in contact with the sur- 
rounding blood, is the syncytium. This is in a more active state of proliferation than 
the zellschicht, large masses of protoplasm are seen budding off, sometimes in long 
club-shaped strands, at others, in small rounded masses. 
Vacuolation of the syncytium is very marked here, giving the appearance of a 
network of protoplasm, with delicately-curved nuclei, following the outline of the 
reticulum. Tracing these to the periphery, it is seen that, wherever the syncytium 
comes into contact with the muscular wall, syncytial cells have penetrated far and 
wide, and plasmodial masses may be observed, having a direct connexion with the 
vesicle on the one hand, and maternal blood spaces, deeply embedded in the muscular 
wall, on the other. 
At a short distance from the vesicle just described, but separated from it 
by muscular tissue, a large clump of cells is seen lying free in a venous channel. 
They correspond in every particular with the syncytium covering the vesicle, and 
are evidently derived from that layer. As the lumen of the vessel is almost entirely 
occupied by this mass of cells, it is probable that multiplication is going on in situ. 
Near to the serous coat more villi are seen, also associated with large haemorrhagic 
areas, some of which shew recent blood and dense leucocytic exudation. Many 
of the blood spaces shew invasion by the syncytium, so that from the microscopical 
