112 MALL. [Vot. XIX. 
the chorion is fibrous and between the few villi covering it 
there is much mucus rich in leucocytes. The embryo is 
atrophic, the tissues, however, being still active, although dis- 
sociated. The brain and head are reduced in size, the medulla 
is solid and fills the region of the face, and the cord is dilated 
and its walls are folded upon itself. The organs are more 
dissociated than before, the large blood-vessels and the heart 
being greatly dilated and filled with blood. The precartilages 
and peripheral nerves are well marked and the remaining 
tissue is pretty well filled with round cells. Most of the 
epidermis is intact. 
The two specimens just described hom to what extent an 
embryo four weeks old may dissociate when its nutrition is 
partly cut off. In the next specimen (336) the amnion did not 
continue to dilate as well as it did in Nos. 285 and 347, but re- 
mained clinging to the embryo, as is the case normally at this 
time. However, it is pretty well destroyed, being partly 
infiltrated with embryo blood-cells. The ccelom is well filled 
with granular magma, in which there are many migrating 
cells. In form the embryo is curled upon itself and distorted. 
Within the central nervous system is dilated and the walls 
are folded upon themselves. The liver is completely infil- 
trated with blood. Mesodermal tissues seem to be normal. 
What is especially noteworthy is the condition of the vascular 
system. The heart walls appear normal and the vascular 
system is well proportioned and filled with blood. It appears 
as if it had functioned until the abortion took place. The 
vessels from the embryo through the umbilical cord to the 
chorion are cut off and the enlarged omphalo-mesenteric ves- 
sels seem to take their place. The walls of the yolk sac are 
necrotic, but have in them large blood-vessels, which on one 
side spread over into the chorion. The old original circula- 
tion has re-established itself and is now connected with the 
chorion in this roundabout way. There are in the chorion 
two kinds of capillaries, degenerate ones which are connected 
with the umbilical vessels and new ones which communicate | 
with the omphalo-mesenteric vessels. 
