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FRED W. STEWART 



cytoplasm. This cytoplasmic increase is little marked in sixteen- 

 day embryos, but the branches of the glossopharyngeus in the 

 tongue show such well-marked clusters of elongate and rounded 

 cell elements (fig. 27) that their neuroblastic character is no 

 longer a matter of doubt. Definitive neuroblasts are found in 

 seventeen-day embryos (fig. 11). They apparently arise, as in 

 the case of the vagus, through a rounding out of the nucleus and 

 through an increase of the cytoplasm in certain of the elongated 



G.S.N. IX 



Fig. 11 Rat embryo, 17 days, Carnoy's 6-3-1. Neuroblasts along fibers of 

 ramus lingualis IX in tongue. Projection drawing, X 500. 



accompanying cells. Rhinehart ('18) has observed sympathetic 

 ganglion cells on fibers of the glossopharyngeal nerve within the 

 tongue. In order to confirm the observations of Rhinehart and 

 to have some check upon my own observations, to establish 

 continuity between the embryonic and the adult condition, four 

 pyridine-silver series through heads of young rats were prepared. 

 In each case it has been possible to locate the constant ganglionic 

 mass described by Rhinehart on the glossopharyngeal nerve 

 near the hyoid bone. It has likewise been discovered in Nissl 

 preparations and the sympathetic character of its cells verified. 



