CRANIAL SYMPATHETIC GANGLIA IN THE PIG 91 



gland (fig. 15, X). These cells may have been carried into the 

 anlage of the gland more or less accidentally or they may be 

 destined to take part in the development of the minute multiple 

 ganglia which are known to exist in the substance of the sub- 

 maxillary gland along the courses of its ducts. 



As in the case of the other cranial sympathetic ganglia, the 

 cells composing the anlage of the submaxillary ganglion, in the 

 earliest stages of development, show the same general characters 

 as the cells in the cerebrospinal ganglia. During the succeeding 

 stages of development, however, the cells in the submaxillary 

 ganglion, like those in the other cranial sympathetic ganglia, 

 remain somewhat smaller than the nervous elements in the cere- 

 brospinal nervous system and do not again betray their obvious 

 relationships with the latter until they have become differentiated 

 into neuroblasts. 



In not a few instances isolated groups of cells of nervous origin 

 were observed closely associated with the branches of the lingual 

 nerve which supply the tongue, as well as in the path of the 

 lingual nerve peripheral to the submaxillary ganglion. I was not 

 able to determine the fate of these minute isolated ganglionic 

 cell-groups. It seems probable that some of them may become 

 aggregated to form a sublingual ganglion. In embryos of the 

 pig 25 to 30 mm. in length, many of these cell-groups still remain 

 isolated and some of the cells have become differentiated into 

 neuroblasts. 



During the earliest stages of its development, the submaxillary 

 ganglion has fibrous connections only with the lingual nerve. 

 This nerve, which is one of the main divisions of the mandibular 

 nerve, doubtless, contains fibers from both the sensory and the 

 motor root of the latter. As already indicated, cells advance 

 peripherally from the semilunar ganglion and from the rhomben- 

 cephalon along the sensory and the motor -roots respectively of 

 the mandibular nerve. It is probable, therefore, that cells from 

 both these sources advance peripherally along the lingual nerve 

 and become incorporated in the submaxillary ganglion. It is 

 also probable that these are the sources of all the cells which 

 enter the anlage of the submaxillary ganglion. The lingual nerve 



