Johnston, Nen^es of Petroinyzonts. 60 1 



among the trigeminal fibers in the floor of the orbit, in the sub- 

 cutaneous tissue dorsal and anterior to the olfactory capsule, etc. 

 The wj-iter has heretofore been very skeptical regarding the 

 presence of ganglion cells in such places as those mentioned. 

 When these were first seen they were taken to be large varicosities, 

 but thousands of varicosities have been compared with these and 

 all are very much smaller in proportion to the thickness of the 

 fibers on which they occurred. Then it was found that while the 

 majority of these cells are bipolar, a considerable part of them 

 have three, four or five processes. Finally there are in many 



Fig. 27. The ganglion cells of fig. 26 under a higher power. Magnification, 300 diameters. 



cases, not in all, the same differences between the processes as we 

 find between the dendrites and neurites of neurones in the central 

 nervous system. 



These cells have not yet been exhaustively studied and I cannot 

 state with any confidence either their anatomical connections or 

 their probable functions. They are found both beneath the skin 

 and beneath the mucosa, in the gills and on the surface of both 

 branchial and parietal muscles, in or near the trunks or branches 

 of the V, VII, IX, X, ventral spinal and hypoglossal ( ?) nerves. 

 In a few cases there are indications that these cells are especially 

 related to blood vessels and this is the only supposition that seems 

 in harmony with their wide distribution. 



