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SECTION IV.

OF THE GRADUAL WASTE OF THE MEMBRANE WHICH SUR*
ROUNDS THE BODY OF A TOOTH, AND THE PERIOD AT
WHICH THE TEMPORARY TEETH IN GENERAL APPEAR.*

The membrane which deposits the earthy matter of the
cortex striatus, does not adhere to, but closely surrounds the
body of the tooth ; but as soon as the neck is formed, the
margin of the membrane adheres to it so firmly at that part,
that it cannot be separated from it, without lacerating several
vessels which pass from it to the bone. The membrane be-
comes much thinner at this part, and I could not separate it
at any period into two lamellae.
As ossification advances on the root or roots, the body of
the tooth rises in the socket, and of course the investing
membrane rises with it. The cortex striatus is first perfect-
ed or crystalized on the cutting edges or protuberances of
the tooth, and proceeds gradually from thence to the neck
where it terminates ; and in proportion as the first part of
the cortex striatus is crystalized, that portion of the mem-
brane which formed it becomes thinner, less vascular, and at
length, having performed the particular function for which it
was designed, is totally wasted or absorbed. The gums
also partake of this tendency to waste, and the tooth gradu-
ally appears through it ; part of the membrane still remains
on the body of the tooth, this however is wasted as the cor-
tex striatus covered by it, attains to perfection. So that all
that portion of the membrane, which loosely surrounded the

Blakrv pages 16 to 26.
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