20 ALBERT KUNTZ 
cells which give rise to the sensory ganglia of the vagi escaped 
destruction. Consequently, small ganglia from which afferent 
vagus fibers may be traced along the oesophagus are present. 
This embryo died just before the close of the fifth day of incuba- 
tion, but was fixed before extensive postmortem changes had 
taken place. The primordia of the sympathetic trunks and 
the prevertebral plexuses are present throughout their entire 
extent. A few cells may be traced from the small vagus ganglia 
along the fibers which emerge from the distal aspects of the 
latter, but none have reached the level of the heart or the roots 
of the lungs. The primordia of the pulmonary, the cardiac, 
and the enteric plexuses are absent. In unoperated embryos 
representing the same stage of development, the primordia of 
the cardiac and the pulmonary plexuses are well established. 
Cell aggregates representing the primordia of the enteric plexuses 
are also present in the walls of the stomach and the upper por- 
tion of the small intestine. The absence of the primordia of the 
vagal sympathetic plexuses in this operated embryo disproves 
conclusively both that the cells which give rise to them are differ- 
entiated in situ and that cells are early displaced from the pri- 
mordia of the sympathetic trunks into the primordia of these 
plexuses. These findings, in conjunction with the fact recorded 
above that the primordia of the oesophageal, the pulmonary, 
the cardiac, and the enteric plexuses arise in the absence of 
the primordia of the sympathetic trunks or any pathways except 
those of the vagi along which cells of cerebrospinal origin could 
advance peripherally, demonstrates the genetic relationship 
of these plexuses to the hindbrain and the vagus nerves. How- 
ever, the embryo which showed absence of the primordia of the 
vagal sympathetic plexuses in the presence of the primordia of 
the sympathetic trunks had not reached the stage of develop- 
ment at which the migration of cells into the sympathetic pri- 
mordia normally ceases. Therefore, a late contribution of 
cells from the primordia of the sympathetic trunks to the vagal 
sympathetic plexuses is not precluded. 
As observed above, a portion of the cells which give rise to 
the sensory ganglia of the vagi escaped destruction in the em- 
