178 ALBERT KUNTZ 



regarding the exact sources and the histogenesis of this gangHon. 

 According to Hoffmann ('85), Ewart ('90), and Chiarugi ('94, 

 '97), it arises from cells which advance from the semilunar 

 ganglion into the oculomotor nerve either directly or by way of 

 the ophthalmic division of the trigeminal nerve. Dohrn ('91) 

 expressed the opinion that in the Elasmobranchii the ciliary 

 ganglion arises from cells which migrate from the midbrain along 

 the path of the oculomotor nerve. Beraneck ('84), Reuter ('97), 

 and Rex ('00) also derived this ganglion from cells present in 

 the oculomotor nerve, but did not determine the exact sources 

 of these cells. According to Carpenter ('06), the ciliary gan- 

 ghon arises in the chick from cells which migrate from the wall of 

 the midbrain along the oculomotor nerve, but later receives 

 some cells which advance peripherally from the semilunar gan- 

 glion along the ophthalmic nerve. The available evidence bearing 

 on the development of the other cranial sympathetic ganglia 

 seemed to favor the assumption that the sphenopalatine, the 

 otic, and the submaxillary are derived exclusively from the semi- 

 lunar ganglion. 



Such in brief was the status of the problem when the present 

 writer initiated a series of studies on the development of the 

 sympathetic nervous system in embryos of types of the several 

 classes of vertebrates. The results of these studies which were 

 published in a series of papers ('09-' 14) indicate that the sympa- 

 thetic bears essentially the same genetic relationship to the cere- 

 brospinal nervous system throughout the vertebrate series. The 

 sympathetic trunks, though differing somewhat in their morpho- 

 genesis in the several classes of vertebrates, arise from cells of 

 cerebrospinal origin which advance peripherally both along the 

 dorsal and ventral roots of the spinal nerves. The cells which 

 give rise to the ganglia of the prevertebral plexuses are derived 

 from the same sources. The sympathetic plexuses related to 

 the vagi, viz., the pulmonary, the cardiac, and the enteric plexuses, 

 except in the aboral portions of the digestive tube, are not ge- 

 netically related to the sympathetic trunks, but arise from cells 

 of cerebrospinal origin which advance peripherally along the 

 paths of the vagi. This finding was corroborated by the work 



