THE DENTAL PULP 225 



terminal organs of the nerve fibres, and says : * We may 

 regard the odontoblast and its peripheral process as an end 

 organ, which, if not itself sensitive, at once transmits sensory 

 impulses to the nerve with which it is connected.' 



He would thus agree with Hopewell Smith's views, but 

 goes further than that author in describing a direct con- 

 tinuation of the pulp process of the odontoblast into a true 

 nerve fibre. 



One is aware that there is some analogy to this mode 

 of termination in the endings of the olfactory nerves. From 

 the olfactory cell with its peripheral termination in the 

 olfactory hairs a nerve process proceeds towards the 

 olfactory bulb, but in this case the olfactory cell is an 

 epiblastic cell and the nerve fibre apparently represents 

 the axon of a true nerve cell. The cell and the nerve fibre 

 are formed from the same layer of the blastoderm. 



Carl Huber, in 1898 (12), by the use of methylene blue, 

 traced nerve fibres to the plexus beneath the odontoblasts, 

 and from that to what he considered their terminations at 

 the inner border of the dentine. In this he corroborated 

 the researches of Retzius (26), who in 1894 traced nerve 

 fibres in the pulp of the mouse to the inner surface of the 

 dentine ; but while Huber does not believe in the possi- 

 bility of their entering the dentine, Retzius appears to be 

 more doubtful on this point, for he says : * In vertical 

 sections the fibres, like a string of tiny beads, stretch 

 between the odontoblasts to the surface, and run a little 

 way tangentially. In a tangential section they can be 

 partially traced under the dentine.' 



Retzius has figured and described the nerve distribution in 

 the teeth of reptiles and fish, and figures them as terminating 

 within the tooth-pulp. 



Morgenstern (21) in 1892 and 1895 published his views 

 on the distribution of the nerves to the hard tissues of the 

 teeth. He made use of Golgi's method and described 

 medullated fibres entering the dentine. He considered that 

 they occupied tubes distinct from the dentinal tubules 

 and also traversed the dentinal tubules, and terminated 

 either at the dentine- enamel margin or in the substance 

 of the enamel, in the knob -shaped enlargements seen 



MUMMERY Q 



