No. 2.] DEVELOPMENT OF THE HUMAN COELOM. A5I 
well as a marked shifting of the organs. With the descent 
of the testis a portion of it is cut off to form the tunica 
vaginalis. 
In embryo II the peritoneal cavity is extremely simple, as 
the figures show, —a simple cavity on each side, communicating 
the one with the other by means of two openings, one above and 
one below the omphalomesenteric duct. Later, as the diaphragm 
descends more and more, the liver 
rotates, and its lobes soon fill the 
peritoneal cavity, while the intestine 
develops out into the cord. The 
Wolffian body, sexual glands, and 
suprarenal capsule fill the dorsal side 
of the cavity and the rudimentary 
pelvis. The whole development of 
the intestine takes place within the 
cord, and finally it is drawn into the 
ees : Fic. 50.— Outline of Pleural and Peri- 
embryos when it is about 30 mm. in cardial Cavities in Embryo No. XLV. 
length. By what process thistakes Enlarsed7 times. 
place I am unable to determine, but 
it must take place very rapidly, for 
I have never seen a human embryo 
in which it is only partly retracted. 
In the pig’s embryo, however, I have 
found the stages in which the in- 
testine is in process of retraction. 
The liver now fills nearly the Fic. 51.— Outline of Pleural and Peri- 
f cardial Cavities in Embryo No. 
whole cavity, and extends down to XXXIV, Enlaiged oedues! ee 
the pelvis, and in embryo XXII ay oo Deak aE Oona Ce 
projects over the ovary and is in 
contact with the rectum. As the intestines are retracted 
from the cord the liver is relatively higher and higher, for 
the expansion of the abdominal walls is now greater below the 
umbilical cord than before, giving more space in this region 
for the intestine which displaces the liver. In embryos 
XXXIV and XLVIII the intestines have been studied, and it 
was found that they were still located in the ventral portion of 
the peritoneal cavity, as there is no pelvic cavity large enough 


