io: I] ORIGIN OF HUMAN MONSTERS. 165 
is a large vesicle, 6 mm. in diameter, with transparent walls. 
This vesicle in turn is partly filled with a granular deposit. 
The syncytium is excessive. The mesoderm of chorion and 
inclosed vesicle is very fibrous. There are blood islands and 
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Fic. 58b. 
Fic. 58c 
Fic. 58b.—Sections through the vesicle at its attachment on the chorion. 
X 10 times. Within the stem there is a sharply defined cavity lined 
with epithelium and an hour-glass-like space filled with blood. On 
one side the stem is covered with epithelium. 
Fic. 58c.—The cavity of the stem, shown in Fig. 58b, enlarged 50 times. 
a cavity lined with epithelium in the stem of the vesicle. The 
main portion of the vesicle is composed of two layers, but 
near the stem there are three layers present. The mesoderm 
of the villi is hyaline and cedematous, and between them there 
is a stringy mass of mucus or fibrin rich in leucocytes. 
