No. 2.] DEVELOPMENT OF THE HUMAN COELOM. 447 
tion has just closed by the walls of the ridge having grown 
together; the extent and shape of the pleural cavity is much as 
it is in Fig. 42. The Wolffian body is smaller, and the kidney 
and suprarenal capsule have come together. 
The story, then, is brief: as the diaphragm descends, its 
dorsal end is in apposition with the suprarenal capsule, and 
finally, when the capsule approaches the twelfth rib, a ridge of 
tissue which also includes the capsule unites with a ridge from 
the septum transversum, and the opening is closed. These two 
ridges, however, are portions of one and the same ridge, as they 
form a circle and in section appear as two ridges. The circle 
is closed much after the fashion of tying up a bag. 
All of the abdominal organs, with the exception of the kidney, 
descend; and the descent is not completed until the pelvis is 
formed to admit some of them. In the stages pictured nearly all 
the small intestine lies in the umbilical cord, as is the case in 
many mammalian embryos. In embryo X (Fig. 45) a large 
portion of the liver also projects into the cord. I have also 
observed a hernia of the liver in another embryo somewhat 
larger. I do not consider the form of embryo X altogether 
normal, but this was not noticed until the reconstruction was 
complete. 
Closely associated with the closing of the pleuro-peritoneal 
opening is the development of the coeliac ganglion. In these 
young embryos it is extremely large, and can be outlined al- 
ready, while the septum transversum is still high in the thorax. 
As the septum descends, the various communicating branches 
of the nerves are caught up with the coeliac ganglion and 
dragged along. This accounts for the high origin of the 
splanchnic nerve. 
Fig. 46 (embryo VI) shows that all the tissues are becoming 
more definitely outlined, and the whole structure is firmer than 
in embryo X. The organs of the abdomen are more firmly 
clustered together, and the intestine has become more con- 
voluted. The lung is much larger, and the pleural cavity ex- 
tends to the ventral wall of the embryo, obscuring wholly the 
outline of the heart. In general it confirms everything given 
in Fig. 45. 
