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niSTOLOGF AND CHEMISTRY OF THE TEETH. 1 149

in the compact and spongy parts of one and the same bone are
not to be attributed to the bony matter itself, but to the whole
bone, including the contents of the lacunse, Haversian canals,
etc. (Hoppe-Seyler).
In the compact matter of the femur of women aged ninety-
seven, eighty-eight, eighty-one, eighty, and twenty-two years re-
spectively, Fremy found the same quantity of organic substance
as in the case of a new-born female child.
In conformity with these and other similar results, Hoppe-
Seyler maintains the unchangeableness of the combinations
occurring in bone, dentine, etc. If Hoppe-Seyler's conception is
correct, the small increase of inorganic matter supposed to occur
in senile teeth is not to be explained by an increased amount of
lime-salts in the dentine, but must be attributed to a decrease in
the volume of the soft tissues of the dentine,—in other words,
by a formation of basis-substance at the expense of the tubular
substance. We shall recur to this question in our remarks upon
the transparency of dentine.
The organic constituent of dentine yields glutine when boiled
with water, and readily undergoes putrefaction.
The enamel contains but two to five per cent, of organic sub-
stance, and usually falls completely to pieces during decalcifica-
tion, unless special precautions are taken. This remnant of the
enamel-forming organ is of epithelial origin, and consequently
yields no glutine when boiled in water.
According to Hoppe-Seyler, bone, dentine, and enamel all
contain (P0,)eCai„C03, or 3[(PO,)2Ca3]CaC03,—that is, saturated
calcium phosphate carbonate in a combination which corresponds
to apatite (P0,)6Cai,jFL.
The following analyses of the ashes of bone, dentine, and
enamel srave values which conform with this view :
Bone.* Deritine.f Enamel.
Ca 37.99 Ca 87.54 Ca 38.31
PO, 54.91 PC), 56.05 PO, 56.20
CO3 4.98 C03 4.79 CO3 5.60
Fl 1.29(?) CI 0.47
Mg 0.83 MCT 0.38

* According 10 Wildt. Average of several analyses.
f
According to Hoppe-Sevler.