Dahlgren, Giafit Ganglion Cell Apparatus. 177 



so-called dorsal root of that nerve receiving its fibers from the 

 root of nervus linese lateralis and from the ramulus ampullae 

 posterioris. 



If the terminal buds, found in such numbers and so irreg- 

 ularly distributed over the head of Amia, represent a stage in 

 the development of the canal organs, they and the nerves inner- 

 vating them should arise in connection with sensory ecto- 

 dermal thickenings, as do the canal organs and their nerves. 

 AUis has shown that those trigeminal and facial nerves, in 

 Amia, that are known to innervate terminal buds or regions 

 where those buds abound, all arise from the median, fasciculus 

 communis portion of the main trigemino-facial ganglion. He 

 thinks it probable, as Strong has suggested, that ' ' the fasiculus 

 communis tract of the brain is largely or entirely concerned in 

 the innervation of terminal buds." 



The chorda tympani belongs probably to the fasciculus 

 communis nerves, and is represented in Amia, by the mandibu- 

 laris internus trigemini. 



There is no true ramus ophthalmicus profundus in Amia, 

 but the ganglion is distinct, and a rudiment of the nerve is 

 sometimes seen. 



The "hitherto undescribed cranial nerve" of Pinkus in 

 Protopterus is found in Amia. 



The Giant Ganglion Cell Apparatus. 

 By Ulric Dahlgren, 



Princeton University. 



The following report, read before the Neurological Semi- 

 nar of the Marine Biological Laboratory in July, 1898, is an 

 outline of some recent work on the problem presented by the 

 "Giant Ganglion Cells " found in the median dorsal fissure of 

 the myelon of a number of fishes. This report includes several 

 recent advances made by the writer on the problem in question. 



