172 FRED W. STEWART 



during the investigation have been met through the Mrs. Dean 

 ^'age Research Fund. The writer wishes to acknowledge the 

 assistance granted. 



OBSERVATIONS 

 Forward growth of the sympathetic of the cervicat region 



The first problem for consideration in the study of the origin 

 of the cranial sympathetic ganglia 2 is that of the forward growth 

 of the sympathetic of the cervical region into the head. Thir- 

 teen-day stages in some cases give no evidence of a superior 

 cervical sympathetic ganglion, and therefore, of course, no 

 internal carotid nerve. In others a sympathetic ganglion is 

 present in connection with the first cervical nerve, but no fusion 

 of cervical sympathetic ganglia has occurred as yet. In embryos 

 thirteen and one-half days old, a tendency toward fusion is 

 noted in the cervical sympathetic ganglia, as evinced by the more 

 scattered arrangement of cells and the establishment of a longi- 

 tudinal connecting strand. In some cases a complete fusion has 

 occurred. Simultaneously with the formation of the longitudinal 

 connecting strand, a forward extension is noted. This anterior 

 extension may be traced forward along the internal carotid 

 artery to a region just dorsal to the pharynx at about the level 

 of the second pharyngeal pouch. The ganglion itself has like- 

 wise grown forward to approximately the third-pouch region, 

 whereas in the earlier stage, the most anterior of the cervical 

 sympathetic ganglia lay somewhat caudal to the fourth-pouch 

 region. This more anterior position of the superior cervical 

 sympathetic ganglion seems the result of a large cell increase in 



2 In this paper the term 'sympathetic' is used in a broad sense to include 

 ganglia of the sympathetic chain, prevertebral ganglia, such as the coeliac, and 

 smaller masses of sympathetic ganglion cells such as are found in the myenteric 

 and submucous plexuses of portions of the alimentary canal and in the various 

 viscera; likewise, the larger ganglionic masses of the head and the so-called 

 ganglionated cephalic plexus (Hardesty, '14). In view of the appointment of a 

 committee, at t Ik- 1916 session of the American Association of Anatomists, to 

 examine and revise it' necessary ( lie presenl terminology used in designating these 

 portion- of the peripheral nervous system, do more elaborate terminology has 

 been employed by the writer in the present paper. 



