246 MALL. [Vor. XIX. 
vessels and an epithelial tube, the allantois, between them. 
At no place is the amnion attached to the chorion, nor are 
there indications that they have been torn apart. 
No. 247. 
Ovum, 40 x 40 x 17 mm.; vesicle, 2% mm. 
yee, 
Dr. Seymour, Trappe, Md. Brodel Collection. 
The ovum was found filled with granular magma and in 
the center of this, far away from the chorion, a free umbilical 
vesicle was found. Sections of the chorion show that it is 
nearly normal in structure without any signs of an amnion on 
its inside. The villi are without capillaries. At points be- 
tween the villi the syncytial cells form mounds below the 
epithelium, which have a tendency to penetrate the mesoderm 
of the chorion. 
The pear-shaped body is probably the umbilical vesicle, 
with a cavity lined with epithelium and a considerable amount 
of mesoderm around it, in which there are numerous blood- 
vessels filled with blood. There are some accessory vesicles 
in this layer similar to those found in No. 78. 
No. 250. 
Ovum, Io x 9 x 9 mm.; embryo, 2 mm. 
Dr. Sampson, Baltimore. 
The specimen came imbedded in a mass of decidua, which 
was obtained by scraping the uterus. When opened it was 
found filled with magma reticulé, in which could be seen, 
immediately beneath the chorion, a small embryo, and further 
away, towards the center of the ccelom, the umbilical vesicle, 
The whole ovum was cut into serial sections. 
The chorion and villi are apparently normal in shape and 
structure, being also very rich in blood-vessels which are filled 
with embryo’s blood. The villi are bathed in mother’s blood 
and covered with an active syncytium. The decidua is some- 
what infiltrated with leucocytes, but there are no abscesses. 
The front end of the amnion is torn and its free edge and 
the embryo are imbedded in reticular magma, indicating that 
