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the posterior or wisdom-teeth three or four. In other re-
spects their formation is exactly similar to that of the tem-
porary grinders, but they are much larger. In the under
jaw they have in general two roots, in the upper three, but
the posterior, though they have sometimes two, three, or
even four distinct roots, seem most commonly to have but
one.

section in.
OF THE PULP, AND FORMATION OF THE BONY PART OF A
TOOTH.*

The pulp seems intended for a purpose similar to that of
the cartilaginous matter of the other bones, though the pro-
cess of its ossification is conducted in a different manner. A
tooth is formed from without inwards, the first part formed
being the outermost layer, which is as large, and probably as
perfect at first, as at any subsequent period of life. I allude
here to that part only of the outermost layer, on which the
fibres of the cortex striatus are afterwards to be arranged.
Ossification commences on the highest or most promi-
nent point of what is afterwards to be the cutting edge or
"rinding surface of the tooth ; as also, on as many points as
there are eminences on the pulp. The bony matter being
first deposited on these points, it necessarily becomes hol-
lowed towards the pulp, and gradually augmenting, at length
forms over it small elastic shells.
On the incisores and cuspidati, whose formation is more

Blake, Essay on the Teeth, in Man, Pages 5 to 15.