154 MALL. HL WAoiEs 2S. 
The mesodermal layer of the chorion is thin and decidedly 
fibrous with but few cells scattered through it. There are no 
villi. There are groups of cells in the chorion, at the base 
of the embryonic vesicle, which are probably islands of syn- 
cytium inclosed within it. 
The walls of the vesicle are thick and fibrous with no blood 
island within them. It is covered with a single layer of 
epithelial cells which have fallen off at points. Scattered 
throughout the mesoderm there are numerous migrating cells. 
At the base of the vesicles there are a few blood spaces with 
blood cells within them. The vesicle is lined with a single 
layer of epithelial cells. 
At the base of the larger vesicle there is a large closed 
space lined with spindle cells. A similar space lies imme- 
diately below the smaller vesicle. 
No. 20. 
Chorion, 20: £46 mm: 
From Dr. J. W. Williams, Baltimore, February 14, 1894. 
From the exterior, the ovum appears to be normal with 
well developed villi of the chorion. Within the ccelom, how- 
ever, there is a great quantity of magma, within which were 
buried several nodules. These were removed and sectioned. 
Fic. 20a. Fic. 2ob. 
Fic. 20a.—Exterior of ovum, showing long irregular villi. Natural size. 
Fic. 20b.—Inside view of chorion, showing strands of magma reticulé. 
Sections show that there is no amnion lining the chorion 
and that the small nodules are only small masses of magma 
which contain no cells. The villi are normal in form with 
the usual quantity of syncytium upon them. At isolated 
points between the villi there are small masses of a granular 
substance which look like coagulated albumin. 
