Treatise Upon the Genesis and Development of the Dental Follicles to the Epoch of the Eruption of the Teeth. [Volume: 2, Issue: 5, December, 1860, pp. 251-260]

252

THE DENTAL COSMOS.

of the jaw is examined, we will see only a solid, dark tissue, slightly areolar at its edges; whereas when we examine a cut at its surface, we find
the osseous substance divided into follicules that circumscribe the areolke,
forming most elegant designs. Respecting the cartilaginous tissue,
(which forms, as before stated, a sort of varnish, by means of the ossification by invasion, on the surface of parts already ossified,) it appears in
the form of a transparent bed, which it is difficult to distinguish from the
surrounding laminated tissue when it is but slightly magnified. The
chondroplasts which it contains, when seen under a magnifying power of
about three hundred diameters, are pale and triangular, or irregularly
polyhedral in shape. In the small cartilaginous lamina that rises above
the osseous edges of the grooves, and in the cartilage of the extremities
of the organ, the chondroplasts are larger, angular, with the angles sometimes prolonged to a point, and contain one or two finely granulated
grayish cells. The chondroplasts give this cartilage the general appearance of the cartilage of ossification in the other parts of the fcetal skeleton, as it is seen when the phenomena of ossification is already consider*ably advanced after birth.
The preceding particularities of texture exist without sensible differences
in all the mammifera.
It is now necessary for us to make a separate examination into the disposition of the inferior and superior maxillaries.
a. Inferior maxillary.
At a period which corresponds in man to the end of the second month,
(between fifty and sixty days,) there is no part of the inferior maxillary
entirely cartilaginous except the condyle, the posterior part of the angle,
and the crown of the coronoid apophysis. All the rest of the organ is
ossified, but covered with a cartilaginous bed, only some hundredths of
a millimetre in thickness; it is a little thicker at the edges of the bone
than it is on its faces. The same condition of things occurs in the hog,
but we have already stated that among ruminating animals the ossification
of the extremities and edges of this maxillary are less advanced. The
lower edge of the latter is thin and regular. The upper edge of the
horizontal or dental portion is furrowed with grooves; thus it is really
double, and each of the edges of the groove is thin and easily broken.
The lower maxillary is at this level almost as broad as it is high; but following its internal structure, it does not offer the resistance that its thickness would seem to indicate.
The groove is worthy of being described with care. It extends without
discontinuity from the anterior edge of the ascending branch of the maxillary, encroaching a little on its inner face, as far as the anterior extremity
of the corresponding branch of the maxillary; consequently the whole of
its contents can be removed in one piece. Yet almost directly after the