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FRED W. STEWART 



these fibers are ganglionated in later stages. Accordingly, some 

 effort must be made to rule out these neuroblasts migrating from 

 the internal carotid nerve if any contribution along fibers of the 

 glossopharyngeal to the small ganglia of the tympanic plexus 

 is to be shown. If the otic ganglion were of trigeminus origin, 



Fig. 12 Rat embryo, 17 days, Carnoy's 6-3-1. 

 geus IX. Projection drawing, X 500. 



Neuroblasts of ramus pharyn- 



it too would have to be considered as a possible source of the 

 neuroblasts of the tympanic plexus, which might then arise 

 through a caudal migration of cells via what in the adult is known 

 as the lesser superficial petrosal nerve. My personal observations 

 have failed to show any developmental relationship between the 

 otic ganglion and the Gasserian ganglion, and I have been forced 

 to the conclusion that the otic ganglion is entirely a ganglion 



