Olfactory Apparatus in Dog, Cat and Man 43 



4. The supporting cells are cylindrical and the inner process is often 

 divided. Stellate cells are found at the base of the supporting cells. 



5. The development of the sense of smell in the dog and the cat may 

 be due to the large number of the olfactory nerves and to the extent of 

 their distribution, and, according to Van Gehuchten, to the number of 

 mitral cells with which each olfactory cell is associated. 



6. The vomeronasal organ is intimately connected with the sense of 

 smell. It contains, at least in the cat, sensory cells apparently identical 

 with those of the olfactory mucosa. 



7. There are free nerve terminations in the olfactory epithelium. 

 These are the endings of the 5th nerve. 



In the position of the olfactory nerve cell we apparently have a 

 primitive condition. This is the only case in vertebrates where the 

 nerve cells are within the epithelium, as are those for the tactile sense 

 in many invertebrate forms. In the other organs of sense there is a 

 gradual recession of the ganglion cell imtil, in the ganglion of the 

 dorsal root of the spinal cord, the central nervous system is approx- 

 imated. The branches for the tactile sense end freely either in special 

 organs (tactile corpuscles) or in the free end-knots within the epithe- 

 lium, but do not reach to the surface of it; while the branches of the 

 nerves of other sense organs end freely among special cells, but do not 

 reach the free surface of the epithelium. In the olfactory region the 

 olfactory hairs are above the free surface of the epithelium and in 

 direct contact with the air. 



BIBLIOGRAPHY. 



Papers starred (*) bave not been consulted, as they were not available. 

 References have been made from articles where these papers were com- 

 mented upon. 

 Aenstein, 1887. Die Methylenblaufarbung als histologische Metbode. Anat. 



Anz., Bd. 2. 

 Barker, L. F., 1899. The Nervous System. 

 1904. Laboratory Manual of Anatomy. 

 Bawden, H. Heath, 1901. A Bibliography of the Literature on the Organ 



and Sense of Smell, Anatomy and Histology, 391 references. Journal 



of Comparative Nenr^Jogy, Vol. 11. 

 Blaue, Julius, 1884, Untersucbungen liber den Bau der Nasenscbleimbaut 



bei Fischen iind Ampbibien, namentlicb iiber Endknospen als End- 



apparate des Nervus olfactorius. Inaugural Dissertation, ArcMv f. 



Anat. 11. Physiol., Anat. Abth. 



