No. 2.] DEVELOPMENT OF THE HUMAN COELOM. ATI 
develop. At that time the fibrous degeneration enclosed the 
embryonic vesicle as well as extended around the whole chorion 
into all of its villi. This, then, arrested the further development 
of the embryo, and the embryonic vesicle simply continued to 
expand. 
This idea is further strengthened by another ovum whose 
history I published on several occasions three years ago. 
The specimen is a good one, having been preserved fairly well, 
and it has every indication of being normal. Since the speci- 
men has been in my hands I have studied it over and over 
again, have photographed many of the sections, and have 
reconstructed it. At first it was very difficult for me to 
interpret it, but finally it appears to me that something defi- 
nite can be said regarding the arrangement of the membranes 
and their relation to older as well as to the pathological and 
presumably younger specimens. 
Embryo No. XI, —‘*The woman, from whom the specimen 
was obtained, is twenty-five years old, menstruates regularly 
every four weeks, the periods lasting from four to five days. 
She gave birth to a child Sept. 19, 1892, and had the first 
recurrence of menstruation December 19. The second period 
followed on January 25, and was very profuse; it lasted until 
February 1. The next period should have begun about Feb- 
ruary 22, but on account of its lapsing the patient concluded 
that she was pregnant, and called at my office a few days later. 
I did not examine her, but asked her to remain quiet and await 
developments, as I thought possible that she might be preg- 
nant. On the evening of March 1 she fell and sprained herself, 
and during the same night had a 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% alcohol.” 2 
The ovum is very large for its age, having a long diameter of 
IO mm. and a short diameter of 7 mm. It is covered with villi 
only around its greatest circumference, having two spots with- 
1 Mall: Anatom. Anz., 1893, and Johns Hopkins Hospital Bulletin, 1893. 
2 Letter from Dr. Kittredge, April 27, 1893. 
