CRANIAL SYMPATHETIC GANGLIA IN THE RAT 



187 



the cardiac plexus, all rich in ganglion cells, enter the hilus of 

 the lung in association with the bronchi, and the pulmonary 

 artery and vein. 



A large number of ganglion cells are encountered along the 

 branches of the superior laryngeal nerve. Certain of these near 

 the vagus trunk are apparently sensory cells continuous with 

 those of the ganglion nodosum. Others (fig. 8) I have considered 

 as sympathetic. Apparently fairly late material is necessary to 

 fully follow the development of the small ganglia of the esopha- 



G.S.N. X 



Fig. 8 Rat embryo, 17 days, Carnoy's 6-3-1. Neuroblasts among fibers of 

 the nervus laryngeus superior. Projection drawing, X 500. 



geal and pharyngeal plexuses. The writer hopes to undertake 

 the investigation as time and material become available. Some 

 attention, however, has been paid to the ramus pharyngeus 

 vagi. The ramus pharyngeus vagi is in later stages so closely 

 related to branches from the cervical sympathetic ganglion and 

 to glossopharyngeal branches, that the study of these older 

 embryos is rather unproductive of definite results. In sixteen- 

 day embryos the ramus pharyngeus vagi may be traced fairly 

 separately into the developing muscularis of the pharynx; at 

 this time no neuroblasts have been found among its branches. 



