Page 82 - My FlipBook

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as the permanent grinder advances and the jaw increases in
length, a process is sent backwards from the upper part of
its membrane, which at first is contained in the same socket.
This process gradually swells into a sac, in which is contained
the pulp, whence the middle grinder is to be formed ; and as
ossification advances, the parts become separated by a bony
partition : the connection however is still kept up. When the
membrane of the middle grinder is tolerably advanced, it
sends off a process in a similar manner, to form the sac of
the posterior grinder or wisdom-tooth.
I think it absolutely necessary to point out in this place
some of the very great oversights and anatomical errors of
Mr. John Hunter ; as his highly respected authority has fre-
quently misled the inexperienced practitioner : he says,*
" The pulp of the first adult incisor, and of the first adult
molaris, begin to appear in a foetus of seven or eight months
;
and five or six months after birth the ossification begins in
them ; soon after birth the pulp of the second incisor and
cuspidatus begin to be formed, and about eight or nine
months afterwards they begin to ossify ; about the fifth or
sixth year the first bicuspis appears ; about the sixth or seventh
the second bicuspis, and the second molaris ; and about the
twelfth, the third molaris or dens sapientis." It is evident that
this description is entirely theoretical ; and not deduced
from anatomical observation
; for not a single point of it
will agree with what I have already demonstrated. How-
ever, he has arranged his plates in such a manner as to make
them correspond in some degree with his doctrine ; for in-
stance in Tab. ix. Fig. 6.f the teeth of a child six or seven
months old are represented, some of the temporary incisores,

Nat. Hist, pages 82 and 83.
t Nat. Hist.