No. 1.] ORIGIN OF HUMAN MONSTERS. 171 
Fic. 78b. Fic. 78c. 
Fic. 78d. 
Fics. 78b, 78c, and 78d.—The sections through the vesicle and chorion. 
x 10 times. Blood is within the cavity of the vesicle. The stem is 
partly covered with epithelium and there is a double amnion, shown 
in Fig. 78b. 
decidua and placenta were passed, weighing together about 
30 grams, the right quantity, it seemed, for a ten-weeks ovum. 
The woman’s husband has been absent for over ten weeks, 
thus making the specimen at least that old. It appears as if 
there had been an arrest of development of the embryo and 
that the membranes continued to grow.” 
When the specimen came into my hands the walls of the 
chorion were perfectly smooth without any villi whatever. It 
was filled with a clear fluid and within there is attached a 
small double vesicle, measuring 1 x .6 mm. This was im- 
bedded and cut into serial sections. 
The chorion is atrophic and has no villi upon it. The 
nodule within is covered with a single layer of epithelial cells 
which becomes thickened over the pedicle. At one point the 
thickening is greatly increased and immediately below it there 
are two small vesicles lined with epithelial cells. The main 
cavity of the vesicle is lined with a layer of cubical cells, and 
is filled with a considerable quantity of round cells. This 
cavity is hour-glass shaped and extends to the walls of the 
chorion, as the figures show. The mesoderm of the vesicle 
