CRANIAL SYMPATHETIC GANGLIA IN THE PIG 93 



ganglia arise, in embryos of the pig, from cells which have their 

 origin in the semilunar ganglion and the walls of the mesenceph- 

 alon and rhombencephalon and advance peripherally along the 

 oculomotor and the several divisions of the trigeminal nerves. 

 These cells, like the cells which give rise to the other parts of the 

 sympathetic nervous system, have their origin in a cerebro-spinal 

 ganglion, i.e., a ganglion which is derived from the neural crest, 

 and in motor niduli in the wall of the neural tube and advance 

 peripherally along sensory and motor nerve-fibers respectively. 

 The oculomotor and the trigeminal nerves, therefore, sustain the 

 same genetic relationship to the cranial sympathetic ganglia as 

 do the spinal nerves to the ganglia of the sympathetic trunks 

 and the prevertebral sympathetic plexuses and the vagi to the 

 vagal sympathetic plexuses. Furthermore, the cells which give 

 rise to the cranial sympathetic ganglia, like the cells which give 

 rise to the other parts of the sympathetic nervous system, are 

 the descendants of the 'germinar cells of His, viz., the 'indifferent' 

 cells and the 'neuroblasts' of Schaper. These ganglia, therefore, 

 arise in an analogous manner and bear the same genetic rela- 

 tionships to the cerebro-spinal nervous system as do the other 

 parts of the sympathetic nervous system Ontogenetic evidence, 

 therefore, warrants the conclusion that these ganglia are sympa- 

 thetic in character. 



As is well known, the sympathetic character of the ciliary 

 ganglion has been questioned by not a few investigators. It is 

 of interest to note, therefore, that the ontogenetic evidence for 

 the sympathetic character of the ciliary, the sphenopalatine, the 

 otic and the submaxillary ganglia presented in this paper is in 

 full accord with the recent histological observations of Miiller 

 and Dahl ('10) w^ho find, in several mammalian types, that all 

 of these ganglia are composed exclusively of multipolar neurones 

 which do not differ materially from the sympathetic neurones in 

 the other parts of the sympathetic nervous system. 



