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fire much larger, and have three, and sometimes four roots,
are supplied by branches proceeding to each root, nearly as
small as hairs."
Doctor Munro has several preparations in his museum, in
which the nerves and vessels were traced by him into the
roots of the teeth, and also into the pulp, which appears suf-
ficiently evident in Tab. I. Fig. 4, &c*
Mr. Hunter observes, " a strong circumstance in support
of the teeth having no circulation in them, is, that they never
change by age, and seem never to undergo any alteration,
when completely formed, but by abrasion ; they do not
grow softer like the other bones, as we find in some cases,
where the whole earthy matter of the bones has been taken
into the constitution. From the foregoing experiments it
would seem that the teeth are without absorbents as well as
other vessels, and are to be considered as extraneous bodies,
with respect to a circulation through their substance."
These remarks of Mr. Hunter are by no means just, for
the bony part of a tooth undergoes changes by age, as well
as any other part of the body. Indeed, if by chance the
vessels which enter the roots and are distributed on the pulp,
be torn or destroyed, the body of the tooth becomes discol-
oured, sometimes nearly black, the external membrane
which surrounds the roots not being sufficient to supply it
with nourishment, so that the bony part acts as a foil to the
cortex striatus. I have frequently observed their roots
changed nearly to a cartilaginous substance, and rendered
perfectly transparent by the absorption of the bony matter.
The roots of the grinders have been so frequently observed
joined together by exostosis, that its occurrence was well
However,
known to Eustachius. nay, even to Hippocrates, f

* Nat. Hist, page 39. t Opuscul. De Dentib. page 97.