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40 HUNTER ON THE TEETH.
This substance makes the interior part of the body, the neck,
manner, and close together towards the surface of the dentine. In the
eiown of the tooth, the dental tubes, at about the middle or outer third
of their course, commence sending off fine ramifications, which are
mostly simple, but sometimes branched. In this situation, a tube will
frequently appear to terminate by dividing into two fine branches. In
the fang, the ramifications are much more numerous than in the crown
they commence earlier in the course of the tube, and sometimes give it
a plumose, or, when the ramifications are long and branched, a brushdike
appearance. These ramifications, by anastomosing, serve to connect
with each other neighbouring or more remote canals. The terminations
of the dentinal tubes are fine in proportion to their amount of ramifica-
tion ; they frequently appear as extremely delicate pale lines, like the
fibrils of connective tissue, and beeome at length so attenuated that
they cannot be farther traced. Where, however, the tubes and their
ramifications can be followed to their termination, they are either found
to form loops in the substance of the dentine itself by the junction of
one tubule with another (terminal loops of the dental canals), or to end
in a granular layer to be hereafter noticed ;—or, passing across the boun-
dary of the dentine, they may be traced into the enamel or crusta
petrosa. (1)
Dentine presents indications of lamelhtion. In a longitudinal section
of a tooth, arched lines more or less parallel to the circumference of
the crown, and situated at a varying distance from each other, are
to be observed. In transverse sections they appear as rings. These
are the contour lines of Professor Owen ; so called from their general
similarity with the contour of the tooth. Mr Salter, who has described
their appearance and arrangement with great minuteness, states, how-
ever, that the course of the contour line never exactly corresponds with
the circumference of the crown of the tooth. " The contour of the two,"
lie writes, "is not identical, for the markings (in whatever part examined)
are more divergent than the outline of the tooth, and, passing from
within outwards, abut in succession upon the external surface of the
dentine. In comparing the absolute contour of any tooth, it will be
found that the angle formed by its sides is more acute at its summit,
or the summit of any particular cusp, than the contour markings
within." (2) In teeth which have more than one cusp, the upper
contour markings are confined to their own cusps, and their extremities
abut against their sides; the lower ones are continuous with those of
continuous cusps. These contour lines or markings are curved in their
course : according to the observer just quoted, the curves are "in pro-
(1) Vide Kolliker, op. cit., p. 281.
(2) On certain Appearances occurring in Dentine, by S. J. A. Salter, Quart,
Journ. Micros. Sci., vol. L, p. 254.
40 HUNTER ON THE TEETH.
This substance makes the interior part of the body, the neck,
manner, and close together towards the surface of the dentine. In the
eiown of the tooth, the dental tubes, at about the middle or outer third
of their course, commence sending off fine ramifications, which are
mostly simple, but sometimes branched. In this situation, a tube will
frequently appear to terminate by dividing into two fine branches. In
the fang, the ramifications are much more numerous than in the crown
they commence earlier in the course of the tube, and sometimes give it
a plumose, or, when the ramifications are long and branched, a brushdike
appearance. These ramifications, by anastomosing, serve to connect
with each other neighbouring or more remote canals. The terminations
of the dentinal tubes are fine in proportion to their amount of ramifica-
tion ; they frequently appear as extremely delicate pale lines, like the
fibrils of connective tissue, and beeome at length so attenuated that
they cannot be farther traced. Where, however, the tubes and their
ramifications can be followed to their termination, they are either found
to form loops in the substance of the dentine itself by the junction of
one tubule with another (terminal loops of the dental canals), or to end
in a granular layer to be hereafter noticed ;—or, passing across the boun-
dary of the dentine, they may be traced into the enamel or crusta
petrosa. (1)
Dentine presents indications of lamelhtion. In a longitudinal section
of a tooth, arched lines more or less parallel to the circumference of
the crown, and situated at a varying distance from each other, are
to be observed. In transverse sections they appear as rings. These
are the contour lines of Professor Owen ; so called from their general
similarity with the contour of the tooth. Mr Salter, who has described
their appearance and arrangement with great minuteness, states, how-
ever, that the course of the contour line never exactly corresponds with
the circumference of the crown of the tooth. " The contour of the two,"
lie writes, "is not identical, for the markings (in whatever part examined)
are more divergent than the outline of the tooth, and, passing from
within outwards, abut in succession upon the external surface of the
dentine. In comparing the absolute contour of any tooth, it will be
found that the angle formed by its sides is more acute at its summit,
or the summit of any particular cusp, than the contour markings
within." (2) In teeth which have more than one cusp, the upper
contour markings are confined to their own cusps, and their extremities
abut against their sides; the lower ones are continuous with those of
continuous cusps. These contour lines or markings are curved in their
course : according to the observer just quoted, the curves are "in pro-
(1) Vide Kolliker, op. cit., p. 281.
(2) On certain Appearances occurring in Dentine, by S. J. A. Salter, Quart,
Journ. Micros. Sci., vol. L, p. 254.
