THE DENTAL PULP 227 



pulp enter the dentinal tubes. He also described the small 

 nodes or enlargements on the fibres. Certain statements of 

 this author as to the passage of nerve fibres across the 

 tubes on the surface of the sectioned dentine and figured 

 as quite independent of the tubes, are difficult to under- 

 stand. He says : ' From the dentigenous substance and 

 in the dentine they ' [the neurofibrils] ' are distributed in the 

 area of the intercellular substance, and take a course indepen- 

 dent of Tomes' fibres, forming a wide-meshed network. 

 Neurofibrillse are also found in the area of Tomes' fibres 

 within the dentinal tubuli. Hence the nerve fibres in the 

 dentine have two courses : one within the basic inter- 

 cellular substance, the other within the dentinal tubuli, 

 and there may be a possible connexion between these fibres. 

 Possibly their function differs, one group governing sensa- 

 tion, the other, nutrition.' A paper on the innervation of 

 the dentine was also published by Fritsch in 1914 (8). 



The present author's own investigations date back to 

 1891, when he made use of various stains in the attempt 

 to demonstrate the distribution of the nerves of the pulp. 

 Pulps treated with weak chromic acid by the method of 

 Boll showed a multitude of fine fibres close to the dentine, 

 but they could not be traced further. 



The iron and tannin method gave much better results, 

 and showed very clearly the connexion of these fine fibres 

 with the medullated fibres of the pulp, 1 and in a few cases 

 the actual passage of the fibre into the dentinal tube, but 

 the demonstration was not sufficiently convincing to be 

 made use of. 



The intra-vitam method with methylene blue was carried 

 out on two occasions once with Professor Miller in Berlin, 

 and was again kindly conducted for the author by Professor 

 Starling at University College. 



These preparations showed an abundance of neurofibrils 

 proceeding to the dentine, but it was impossible to obtain 

 sections, as the colour cannot be retained during decalcifica- 

 tion. The recent results have been obtained with a modi- 

 fication of the Beckwith gold chloride method, the specimens, 



1 Tomes, C. & A Manual of Dental Anatomy, 7th ed., p. 79. 

 Q 2 



