IVORY OF THE TEETH. 103 
If a tooth be removed from its capsule, and macerated 
for some days in slightly diluted hydrochloric 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 pl. III, fig. 5.) These fibres are too thick to be the 
walls of the tubes; they 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 lay immediately 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 Raschkow, 
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 are more regularly 
arranged, and more extended in the longitudinal direction, 
