200 ALBERT KUNTZ 



still contains small aggregates of ganglion cells. Migrant cells 

 are always more numerous at the periphery than in the interior 

 of the larger nerve trunks. Inasmuch as the otic ganglion lies 

 in immediate contact with the mandibular nerve, many of the 

 cells advancing distally at the periphery of this nerve doubtless 

 become incorporated in the ganglion. At any rate, a contribu- • 

 tion of cells from the mandibular nerve to the otic ganglion can- 

 not be precluded. Indeed, the majority of the cells which enter 

 the otic ganglion probably come from this source. As in the case 

 of the sphenopalatine ganglion, it may be observed that migra- 

 tion of cells into the otic ganglion continues later along the tri-* 

 geminal fibers than along the other contributing path. There- 

 fore, we are forced to conclude that, while the early primordium 

 of the otic ganglion arises at the growing extremity of the lesser 

 superficial petrosal nerve primarily from cells which advance 

 from the petrosal ganglion, the majority of the cells which enter 

 this ganglion are derived from the semilunar ganglion and the 

 motor root of the trigeminal nerve. 



In embryos 14 mm. and over in length the otic and spheno- 

 palatine ganglia are connected with each other by a cellular 

 strand (fig. 29). This cellular connection was observed in em- 

 bryos up to 21 mm. in length, but not in later stages. It prob- 

 ably undergoes retrogressive changes during later development. 

 The significance of this connection, if it has any, could not be 

 determined. 



The writer's earlier observations on the development of the 

 otic ganglion in embryos of the pig led him to conclude that this 

 ganglion arises primarily from cells of trigeminal origin. Further 

 observations on early pig embryos have convinced him that he 

 failed in his earlier work to recognize the lesser superficial petro- 

 sal nerve as a path along which cells advance into the otic gan- 

 glion until the period of most active migration along this path 

 had elapsed. In embryos of the pig, as in human embryos, the 

 first cells which enter the primordium of the otic ganglion ad- 

 vance peripherally along the lesser superficial petrosal nerve pri- 

 marily from the petrosal ganglion, while the majority of the 

 cells which enter this ganglion advance peripherally along the 

 mandibular nerve and its rami. 



