226 MICROSCOPIC ANATOMY OF THE TEETH 



often at the crown of the tooth projecting into the enamel 

 (the spindles). 



We should be very unwilling to translate the thick 

 black lines often obtained in the dentine in Golgi prepara- 

 tions as medullated nerves ; they appear more in the nature 

 of irregular deposits of the chromate of silver, and these 

 appearances probably led this observer to the extraordinary 

 conclusion at which he arrived. 



Professor Homer of Strassburg (28) has been for several 

 years engaged in an investigation of the nerves of the 

 teeth. There is little doubt he succeeded in tracing nerve 

 fibres into the dentine, but he was unable to carry conviction 

 with the few preparations he procured, and his statement 

 that the nerve fibres enter the dentinal fibril (which he 

 considers to be a tube) has not been substantiated. He 

 considered that there was a normal termination of the nerves 

 to be found in the spindles at the enamel margin. 



Pont, in 1900 (24), compared the odontoblasts to peripheral 

 neurons (nerve cells with their processes), which occur in 

 other peripheral organs such as the retina, and considered 

 that the nerve fibres, without forming any direct anatomical 

 communication with the odontoblast, formed synapses, that 

 is, that the nerves which envelop the cell transmit sensation 

 from the cell to the afferent nerve, actual anatomical con- 

 nexion not being necessary for the transmission of impulses 

 from the peripheral cells. The same objection would hold 

 good here that applies to Hopewell Smith's view, that we 

 should not expect a synaptic any more than a direct com- 

 munication between a cell formed from the mesodermic 

 layer and a true nerve fibre of ectodermic origin. It is now 

 generally considered that independent neurons never form 

 direct communications, but that all such between individual 

 nerve cells and their processes with neighbouring cells are 

 synaptic. 



Since the publication of the author's paper in 1912 

 the late Professor Dependorf of Leipzig has published the 

 results of his researches on the same subject (3). He 

 employed many different staining and impregnation methods, 

 usually staining small pieces of teeth in bulk, and he corrobo- 

 rated the author's observation that the nerve fibres of the 



