Olfactory Apparatus in Dog, Cat and Man 39 



median and caudal parts it is kidne3'-shaped and the epithelium is 

 columnar. The median and lateral epithelia differ in thiclaiess; the 

 median is sometimes two or three times thicker than the lateral. In 

 the human which were examined the vomeronasal organ of a 6-7 weeks 

 embryo was flattened as descril)ed for the dog and the cat and man, and 

 the epithelium of the median wall was the thicker. In a four months 

 human fetus it seemed to be circular in outline for its entire length, with 

 a uniform thickness of epithelium. 



The epithelium, like that of the nasal cavity, consists of sustentacular 

 cells and are longer and narrower than those of the nasal mucosa; the 

 sensory cells found in cat had a process which passed to the surface 

 of the ej)ithelium (Figs. 54a, 55a). These cells have not been found 

 in man, according to Mihalkovics, 1898, and Quain, 1906. According to 

 Klein, the sensory cells are found only in the thick median epithelium, 

 von Lenhossek found olfactory cells in the median and lateral epithelium 

 of an embryo kitten. The central process undivided and imbranched 

 passes into the submucosa as a fine varicose nerve fiber. No olfactory 

 hairs were found by von Lenhossek, 1882, as a precipitate was present. 

 He saw in the deeper layers of the epithelium of the vomeronasal organ 

 free nerve endings. An end knot was always present, but a little rod 

 often projected beyond this; according to him, these were either free 

 endings of the 5tli nerve or of olfactory nerves whose cells were some- 

 where in the olfactory course. 



von Brunn in Golgi preparations of the vomeronasal organ of the 

 sheep saw the connection of the olfactory cell and nerve. He also found 

 olfactory hairs. 



Personal Observations. 



Gross Anatomy. 



The gross anatomy of the organon vomeronasale, or Jacobson's organ, 

 has been carefully worked out. As has been previously stated, the large 

 nerves of the nose lie in the deepest layers of the mucosa next to the 

 bone. In order to see these, it is necessary to remove the bone and thus 

 to expose the back or deepest parts of this mucosa. The nitric acid 

 method described above made this possible. The mucosa was freed 

 from the cartilaginous septum, being careful not to tear the nerves 

 which lie almost on the bone. Figs. 2, 4, 8, 9 show such a dissection. 

 'In the doo; and the cat the vomeronasal organ was also intimately con- 



