76 MALL. [VoL. XIX. 
had every reason to believe that the abortion was produced 
through mechanical means, a circumstance which I have since 
learned does not insure a normal embryo. When I received 
the specimen (1893) sketches of it were submitted to Pro- 
fessors Minot and Graf Spee, who discussed it quite exten- 
sively in their letters to me, and they both felt that more 
young specimens would have to be studied before this could 
be properly interpreted. Professor His, however, to whom 
the sections were shown, was inclined to think the embryo 
normal, and as such it was first published. At present it 
seems to me that the ovum was normal until the woman 
“sprained herself six. days before the abortion.’”’ The sprain 
was followed by a flow of blood each day until the abortion 
occurred. Thus it happened, it seems to me, that the chorion 
grew large and the villi small; certainly they are not as well 
developed as in the other young ova given in Table I. 
Through some means, possibly mechanical, the amnion be- 
came torn and the ectoderm spread itself partly over the 
ceelomic side of the yolk sac and belly stalk. The amnion in 
Peters’s ovum is very delicate at one point, being composed 
of but a layer of ectodermal cells, and in Van Heukelom’s 
there appear to be actual openings in the amnion. With these 
facts before us, it is not remarkable that a break should occur 
at this point occasionally. 
Another very valuable specimen is No. 396, which was ob- 
tained from a tubal pregnancy. Within the ccelom of the 
ovum there is a double sac, one of which is clearly the umbilical 
vesicle, and the other may represent the amnion and embryo. 
What is especially interesting in this specimen is the relation 
of the umbilical vesicle to the chorion. At a number of 
points they come in contact, are adherent, and the blood- 
vessels from the umbilical vesicle pass directly over into the 
chorion, from which they spread into its villi. This specimen 
proves that the presence of blood-vessels in the chorion is 
not dependent upon the development of the body of the 
embryo. They may grow to it in a direct way. 
A third specimen (No. 134), much like No. 11, also ob- 
