HISTOGENESIS OF SYMPATHETIC SYSTEM 9 
and the rabbit. He expressed the opinion that it is essentially 
these cells which give rise to the neurons in the sympathetic 
nervous system. Cajal (’08) expressed essentially the same 
opinion based on observations made on embryos of the chick. 
The work of Froriep was attacked by later investigators, notably 
Held (09) and Marcus (’09), who still adhered to the older 
teaching. The writer has since 1909 maintained that cells of 
medullary origin play an important part in the development of 
the sympathetic nervous system and that the primordia of the 
sympathetic trunks receive a large contribution of such cells 
via the paths of the ventral roots of the spinal nerves. This 
view is also supported by the work of Ganfini (11-18), who 
published extensive and detailed observations on the develop- 
ment of the sympathetic nervous system in embryos of types of 
all the classes of vertebrates above the Elasmobranchii. Al- 
though supported by exhaustive studies, this view was opposed 
by Neal (14), who still maintained that a contribution of cells 
of medullary origin to the primordia of the sympathetic trunks 
had not been demonstrated. More recently, Miller (’20) once 
more traced the cells which give rise to the ganglia of the sym- 
pathetic trunks exclusively from the spinal ganglia. 
In an earlier paper (Kuntz and Batson, ’20), experimental 
evidence was presented which demonstrates a definite develop- 
mental relationship of the ganglia of the sympathetic trunks 
to the ventral roots of the spinal nerves. In embryos of the 
chick which were subjected to operation before cells of nervous 
origm had advanced peripherally, the primordia of the sym- 
pathetic trunks arose, in the absence of spinal ganglia and dorsal 
nerve-roots, exclusively from cells of medullary origin which 
advanced peripherally along the paths of the ventral roots of 
the spinal nerves. It was pointed out, further, that the facts 
observed do not exclude the spinal ganglia as a source from which 
cells may enter the primordia of the sympathetic trunks under 
normal conditions. It was also pointed out that the primordia 
of the sympathetic trunks may be of approximately normal size 
in segments in which the spinal ganglia and dorsal nerve-roots 
are absent and the remnant of the neural tube is relatively large, 
