NERVUS TERMINALIS IN AMIA 113 



these nerve cells, peripherally as well as intra-cranially, were 

 often found branching along the walls of the arteries. In other 

 cases the nerve fibers arborize about the ganglion cells of the ner- 

 vus terminalis, as sympathetic fibers are supposed to do. There 

 is ample provision in Amia for connection with the post-optic 

 sympathetic system, and it is difficult to account for a compact 

 bundle along the arteries beneath the olfactory bulbs and the fore- 

 brain on any other supposition. 



It is evident from the literature cited that the nervus terminalis 

 cannot be considered a nerve peculiar to primitive vertebrates, 

 as seemed probable so long as it was found in the generalized 

 fishes exclusively. It appears more and more probable that there 

 is a ganglionated nerve associated with the olfactory nerve through- 

 out the vertebrate series. Aichel ('95) cites a number of authors 

 who have found fibers in the nasal capsules differing from olfac- 

 tory fibers. Some of these fibers are described as coarser than 

 the olfactory fibers, while others are said to be smaller. In most 

 instances they were attributed to the trigeminus nerve, but in 

 light of our present knowledge the whole matter needs to be gone 

 over again to determine whether they belong to the nervus ter- 

 minalis, although we know that in some instances a ramus of the 

 trigeminus nerve enters the nasal capsule. 



SUMMARY OF RESULTS 



1. This paper confirms the work of Allis in finding a ganglion- 

 ated nerve in Amia, which is probably homologous with the nerve 

 first discovered by Pinkus in Protopterus, and with the nervus 

 terminalis found by Locy in a large number of sharks. 



2. The ganglion of the nervus te v minalis in Amia originates 

 in common with the olfactory nerve, from an ectodermal placode. 



3. In early stages the cells of the ganglion cannot be distin- 

 guished from the undifferentiated mass of cells which produce 

 sheath cells of the fila olfactoria. 



4. Incidentally, we have confirmed the results of recent inves- 

 tigators who find the olfactory neurones of the first order arising 

 in the ectoderm and remaining there in the adult. 



