SYMPATHETIC NERVOUS SYSTEM IN MAN 177 



the primordia of the sympathetic trunks and expressed the opin- 

 ion that it is essentially these cells which give rise to the neurones 

 in the sympathetic nervous system. Cajal ('08) expressed essen- 

 tially the same opinion. His observations on embryos of the 

 chick led him to the conclusion that the sympathetic cells are 

 true motor cells which are derived from the spinal cord. 



The work of Froriep was attacked most vigorously by Held 

 ('09) and Marcus ('09), both of whom adhere to the older theory, 

 according to which the cerebrospinal ganglia (or the neural crest) 

 constitute the sole source of the cells which enter the primordia 

 of the sympathetic nervous system. Perhaps no one among the 

 more recent investigators would concur in the opinion of Froriep 

 and Cajal that all sympathetic neurones are derived from cells 

 of medullary origin which advance peripherally along the fibers 

 of the motor nerve roots; however, their conclusion that cells 

 of this type enter the primordia of the sympathetic trunks has 

 been amply confirmed. 



The older investigators studied primarily the development of 

 the sympathetic trunks and the sympathetic plexuses along the 

 abdominal aorta. No extensive observations on the develop- 

 ment of the sympathetic plexuses related to the vagi, viz., the 

 pulmonary, the cardiac, and the enteric plexuses, were recorded 

 prior to the publication of the earlier work of the present writer 

 in 1909 and 1910; however, it was generally assumed that the 

 cells which give rise to the neurones in these plexuses are derived 

 from the primordia of the sympathetic trunks. The earlier work 

 of Abel ('10) is in full accord with this general assumption. She 

 derived the enteric plexuses in the chick from cells which migrate 

 ''from the spinal cord and the intervertebral ganglia downward 

 through the mesentery to the gut." The later work of Abel 

 will be referred to presently. 



Observations on the development of the cranial portion of the 

 sympathetic nervous system, except the ciliary ganglion, which 

 were published prior to the beginning of the past decade are 

 fragmentary and incomplete. The scattered literature bearing 

 on the development of the ciliary ganglion was reviewed by Car- 

 penter ('06). This review reveals a wide difference of opinion 



