CRANIAL SYMPATHETIC GANGLIA IN THE RAT 195 



strands connecting the trigeminus with the otic ganglion are 

 to be noted in sixteen-day embryos. The sympathetic root is 

 likewise apparent. Neither of these have the appearance of 

 migration paths. In the pig, 17.5-mm. stages have shown small 

 aggregates of ganglion cells along the ramus palatinus IX well 

 posterior to the otic ganglion. Although no attempt has been 

 made to follow these in the pig, they are probably to be thought 

 of as belonging to the glossopharyngeal contribution to tympanic 

 plexus. 



In sixteen-day rat embryos, the ramus palatinus IX contains 

 numerous neuroblasts throughout its course from the ganglion 

 petrosum to the otic ganglion; some tendency toward the for- 

 mation of cell aggregates is noted, and in two seventeen-day 

 embryos examined the ganglion cells on the ramus palatinus 

 IX were found to consist of three bilaterally symmetrical groups. 

 The first ganglion appears at the point of origin of the ramus 

 palatinus IX (at this stage slightly distant from the ganglion 

 petrosum) ; the second (fig. 29) appears at the junction of ramus 

 palatinus IX with the inferior caroticotympanic nerve, and the 

 third at the point of union with the superior caroticotympanic 

 nerve (fig. 30). Were it not for the general distribution of 

 neuroblasts throughout the ramus palatinus in earlier stages, 

 examination of seventeen-day embryos might convey the impres- 

 sion that all of the neuroblasts within the tympanic plexus 

 originated along the caroticotympanic nerves from the superior 

 cervical sympathetic ganglion. In view of this more general 

 distribution, however, the writer is inclined to believe that the 

 cells are of double origin, along the glossopharyngeal and from 

 the superior cervical sympathetic ganglion. 



Facialis portion of the sympathetic 



Kuntz ('13) has concluded that in the pig the sphenopalatine 

 ganglion arises along the medial surface of the maxillary division 

 of the trigeminus, from cells which wander peripherally from 

 the semilunar ganglion. Streeter ('12) likewise derives the 

 sphenopalatine ganglion from the semilunar ganglion, calling 



