146 MALT [Vou XIX. 
scanty flow. The flow recurred each day, and on the 7th of 
March she passed the ovum. It was kept in a cool, moist 
cloth for twenty hours, and when it came into my hands was 
at once placed in a large quantity of 60 per cent alcohol.” 
The ovum is very large for its age, having a long diameter 
of 10 mm. and a short diameter of 7 mm. It is covered with 
villi only around its greatest circumference, having two spots 
without villi, as was the case with Reichert’s ovum. The 
villi of the chorion are from 0.5 to 0.7 mm. long, are branched 
and are somewhat fibrous in structure. 
Upon opening the chorion it was found that the embryonic 
vesicle is situated just opposite the edge of the zone of villi. 
Fic. t1c.—Section through the umbilical vesicle and its invagination of 
specimen. > 50 times. The three layers correspond with the ecto- 
derm, mesoderm and entoderm. The invagination marks the cavity 
of the amnion. 
About it there is a considerable quantity of magma reticulé, 
which I did not remove, and therefore could not obtain good 
camera drawings. The portion of the chorion to which the 
vesicle is attached was cut out and stained with alum cochineal 
and cleared in oil, but even after this treatment it was impos- 
sible to obtain any clear picture. The specimen was next 
imbedded in paraffin and cut into sections 10 microns thick. 
The series proved to be perfect. From the sections a recon- 
struction was made in wax. . 
The dimensions of the different portions of the vesicle are 
as follows: 
