Page 597 - My FlipBook

A MELIFICA TION. 607
" These clianges are not easy to follow ; in many preparations it is
impossible to make anything out, and the drawings have been made
from most fortunate preparations selected from some thousands of
sections prepared in various ways.
" The cuticula dentis, then, is formed by the metamorphosis of more
or less of the enamel-cells, and this metamorphosis may begin before
Fig. 338.

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A portion of a Longitudinal Vertical Section of the Upper Small lucisor of a Rabbit: em, 1, 2, 3, 4, "i,
are cells of the enamel-membrane drawn at intervals, showing their gradual change as they
approach the crown of the tooth, until, on its exposed portion, they form :i homogeneous mem-
brane. Obj. F. Zeiss.
any calcification of the underlying dental tissues. In this stage it has
been frequently taken for the ' newly-formed layer of enamel,' for the
'basement-membrane,' and for the ' fir,st-formed layer of dentine.'"
It is evident that if the prisms dejjend upon the shape of the amelo-
blasts for their form the lime salts laid down from this altered mem-
brane would differ materially from the secretion from the ends of the
prismatic ameloblasts, and so we find it.
The analogy between the internal layer of the Pinna, which we have
before studied, and the outer layer of enamel, is complete. Each
individual prism of enamel is the work of a single aiueloblast ; the