IVORY OF THE TEETH. 103 



If a tootli be removed from its capsule, and macerated 

 for some days in Bliffhtly diluted hvdroelUoric acid, the dental 

 substance, which on the first withdrawal of the calcareous salts 

 possessed a cartilaginous consistence, becomes so very soft that 

 it can only be removed from the acid in very small portions 

 with the forceps. This pappy mass is found on examination 

 to consist of fibres, which may here and there be insulated. 

 (See pi. Ill, fig. 5.) These fibres arc too thick to be the 

 walls of the tubes ; thev form the entire substance. Nor 

 can they well be an artificial product, the result of the acid 

 penetrating into the tubes, and dissolving, in the first instance, 

 the substance in immediate contact with them, so that the 

 intercellular substance remained undissolved in the form of a 

 fibre ; they are too regular and smooth for that. It appears 

 rather that the dental substance is composed of these fibres, 

 which have become blended together, that they are therefore 

 identical with those fibres, by the coalescence of which, accor- 

 ding to Purkinje and Raschkow, the dental cartilage is formed, 

 and that this coalescence is not so complete, but that it may 

 be artificially dissolved. The fibres have the same course as 

 the tubes in human teeth, but I could no longer perceive the 

 tubes between them in this preparation ; I could, however, 

 recognize the fibres everywhere, save in the most external layers 

 which lav immediatelv under the enamel, in which situation 

 the mass was more completely broken down by the acid, and 

 traversed by more minute fibres of a different kind, having 

 the most confused and varied directions, and which I suppose 

 to have been the remains of the dental tubes. 



We must therefore regard the dental substance as composed 

 of fibres blended together, between which run tubes provided 

 with special walls. The fibres and tubes are nearly per- 

 pendicular to the dental cavity in human teeth. "What con- 

 nexion now is there between the fibres, or the tubes, and cells ? 

 I should incline to the old opinion, that the dental substance 

 is the ossified pulp. According to Purkinje and Paschkow, 

 the pulp in the first instance consists of globules, of nearly 

 uniform appearance, but has neither vessels nor nerves. At a 

 subsequent period vessels appear in it, and afterwards nerves. 

 Upon the surface of the pulp, the globules arc more regularly 

 arranged, and more extended in the longitudinal direction, 



