196 ALBERT KUNTZ 



maxillary ramus, while the nerve of the pterygoid canal is rela- 

 tively free from cells. Obviously, migration of cells into the 

 sphenopalatine ganglion continues longer from the semilunar 

 than from the geniculate ganglion. That the cells associated 

 with the rami of the maxillary nerve which enter the sphenopala- 

 tine ganglion are at least in part cells which become differentiated 

 into neurones is evidenced by the fact that in embryos 20 mm. and 

 over in length many of them may be recognized as neuroblasts. 

 Furthermore, as observed by Macklin,'^ ganglionic masses of 

 neuroblasts occur on these rami or at their origin from the 

 maxillary nerve in embryos 40 mm. and over in length. The 

 deep petrosal joins the greater superficial petrosal nerve before 

 migration of cells along the fibers of the latter ceases; however, 

 there is no clear evidence that cells which accompany the fibers 

 of the deep petrosal nerve enter the sphenopalatine ganglion. 



The observations here set forth justify the conclusion that in 

 human embryos the sphenopalatine ganglion arises in part from 

 cells which advance from the geniculate ganglion along the 

 greater superficial petrosal nerve and in part from cells which 

 advance from the semilunar ganglion along the maxillary nerve 

 and its rami. Obviously, the contribution of cells from the latter 

 source is greater than that from the former. The writer's earlier 

 observations on the development of the sphenopalatine ganglion 

 in embryos of the pig ('13) led him to the conclusion that this 

 ganglion arises primarily from cells which advance from the 

 semilunar ganglion along the maxillary nerve and its rami, and 

 that it receives relatively few cells from the geniculate ganglion 

 via the greater superficial petrosal nerve. A reinvestigation of 

 the development of this ganglion in embryos of the pig has con- 

 vinced the writer that he failed in his earlier work to recognize 

 the greater superficial petros^-l nerve as a migration path until 

 cells could already be traced from the semilunar ganglion into 

 the primordium of the sphenopalatine ganglion. In embryos of 

 the pig, as in human embryos, the earliest cells which enter the 

 primordium of the sphenopalatine ganglion advance peripherally 

 along the greater superficial petrosal nerve. Nevertheless, the 



^ Unpublished communication. 



