24: Effie A. Head 



lengths. The central process had a straight or undulating course. It 

 often passed just under the epithelial layer for some distance and then 

 entered the mucosa to join the olfactory bundle which passed through 

 the foramina of the cribriform plate to the olfactory bulb. The fiber 

 remained often the same width from the olfactory cell to the olfactory 

 bulb; it did not anastomose or divide, at least not before its entrance 

 into the olfactory bulb. 



In mouse at the transition point between respiratory and olfactory 

 epithelium, Eetzius has seen free nerve endings reaching nearly to the 

 surface of the epithelium. He describes them as very fine and varicose, 

 only here and there were small end knots seen, and these did not differ 

 from the varicosities found on the nerve fiber and were not true end 

 knots. He suspects that they are the endings of the 5th nerve, l)ut is 

 not willing to give this verdict. 



Cajal, ISOJf, speaks of his results thus : Our observations prove not 

 only the continuation of a fiber of the olfactory nerves with a bipolar 

 cell of the mucosa, but also the unity and independence of this fiber in 

 all its course as far as the bulb, where it ends by means of a free 

 arborization. The network and the ramification described in the intra 

 or extra epithelial course of these nerves he has not confirmed by the new 

 methods of coloration. 



Morrill, 1898, investigated the olfactory organ of dog-fish, using 

 Ehrlich's method. He found continuity of the nerve fiber and cell, and 

 also found free nerve endings. He describes three types of olfactory 

 cells, cylindrical, spindle-shaped and conical; whether the difference in 

 shape is due to function or to mechanical causes has not been determined. 



Wiih Reference to the Gross Anatomy of the Olfactory Nerves. — Up 

 to a comparatively short period the olfactory tracts were called olfactory 

 nerves; and further, in speaking of the filaments in the nasal mucosa 

 it was always assumed that they extended from the olfactory bulb. In 

 the newer literature, the nerves are described as extending fi-om tlie 

 olfactory epithelium to the olfactory bulli. They are so considered in 

 this paper. 



Relation of the Olfactory Fibers and Bundles to the Olfactory 

 Mucosa. — In the newest and most reliable works on anatomy of tlie 

 present time the authors describe, in their explanations of the olfactory 

 regions of man both for the nasal septum and lateral wall of the nose, 

 a plexus of the large nerve bundles before they pass through the cribri- 

 form plate of the ethmoid bone. In many cases the figures of Leveille 



