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50 HUNTER ON THE TEETH.
after calcination, so that it is in some measure kept together by
cohesion ; and it is capable of being extracted by steeping in
the muriatic, and some other acids. The animal substance,
when deprived of the earthy part, by steeping in an acid, is more
compact than the same substance in other bones, but still is soft
and flexible, (r)

substance is composed. (1) His observations have not, however, been
confirmed by those of any other writer on the dental tissues.
Dentine exhibiting Haversian canals (the vaso-dentine of Owen) is
very rarely seen in Man, although it occurs in many animals. The
dentine which is produced in cases of obliteration of the pulp cavity
in. iv, however, exhibit a few Haversian canals, and rounded cavities
resembling lacunce: this has been described by Prof. Owen under the
name of osteo-dentine. (2)]
(r) [The organic basis of dentine (tooth cartilage) is identical chemically
with that of bone
: it is, by boiling, readily converted into gelatine.
When separated by treating dentine with hydrochloric acid, it retains
not only the form, but the internal structure of the tissue : the tubes,
however, are not so easily visible. Kolliker states that if tooth cartilage
" be macerated in acids or alkalies until it is quite soft, the matrix is
found in the act of disintegration ; but the dentinal tubes, with their
walls, are still preserved, and may be isolated in large quantities." The
tubes may also be isolated after long-continued boiling. By prolonged
maceration in acids or alkalies, the whole of the organic basis is dis-
solved.
The following is the chemical composition of dry dentine according to
VonBibra:(3)
Molar Tooth of a Man.
Phosphate of Lime and some Fluoride of
Calcium 6672
Carbonate of Lime 336
Phosphate of Magnesia 1-08
Salts 0-83
Cartilage 27-61
Fat 0-40
100-00
Organic substances ------ 28-01
Inorganic substances - 71-99]
(1) Nasmyth, Researches, pp. 93, 94.
(2) Vide Kolliker, op. et loc. cit.
(3) Kolliker, op. cit., p. 292.