the protector of the teeth, and when that is destroyed, you may say good-
bye to the teeth themselves. All acids eat into the enamel, as vinegar or
lemon-juice does into marble; and one of the best means of preserving
this protecting armor of the teeth is never to eat the unripe windfalls
of fruit, which I have seen unreasonable children pick up in orchards
and devour so recklessly. They give sufficient warning, by their
acidity, that they are not fit for food, and when this warning is
neglected, they take their revenge by corroding the enamel of the
teeth; not to speak of the disturbance which they afterwards cause in
the poor stomach.

I said that without this coating of enamel, the teeth would be
prematurely worn out, the reason of which is, that the teeth have not
the property of growing again, as the nails and hair have. When those
little germs of which I spoke when we began to describe the teeth,
have finished their work, they perish and fall out, like masons who,
when they have built the house, take their departure forever.

But the "forever" wants explanation. For such stern conditions would
fall hard on very little children, who, not having come to their reason,
cannot be expected to understand the great value of their teeth, and
take all the care they need of them. So to them _a second_ chance
is given.

Your first teeth, the _milk-teeth_, as they are called, count for
nothing: they are a kind of specimen, just to serve while you are very
young.

When you are approaching what is called the age of reason, (and this
word implies a great deal, my dear child,) the real teeth, the teeth