which are to serve you for life, begin to whisper among themselves,
"Now, here is a little girl who is becoming reasonable, and who will
soon, or else never, be fit to take charge of her teeth." No sooner
said than done: other masons set to work in other cells, placed under
the first set, and as the permanent teeth keep growing and growing,
they gradually push out the milk-teeth, which were only keeping their
places ready for them till they came.

This is just your case at present, and you now understand your
responsibility, and how necessary it is to preserve those good teeth
which have placed so generous a confidence in your care of them, and
which, once gone, can never be replaced.

You have no loss by the exchange; you had twenty-four at first, you
will now have twenty-eight. Twenty-eight, did I say? nay, you will
have thirty-two; but the last four will come later still. The last
_molars_ on each side, above and below, in both jaws, will not
make their appearance till you are grown up. They are a fastidious and
timid set, and will not run any risks; and they are called
_wisdom-teeth_, because they do not appear till we are supposed
to have arrived at years of discretion. Some people do not cut them
before they are thirty, and you will agree that, if they have not
become wise by that time, they have but a very poor chance of ever
being so!

There is much more still to be said about the teeth; but I think I
have told you quite enough to teach you the importance of these little
bony possessions of yours, which children do not always value as they
deserve, and whose safety they endanger as carelessly as if they had
fresh supplies of them ready in their pockets. If so many skilful