constitutional disturbance that, to a
greater or less degree, is experienced by all infants, may be made
intelligible to those who have the care of children, we shall commence
by giving a brief account of the formation of the teeth, the age at
which they appear in the mouth, and the order in which they pierce the
gums. The organs of mastication in the adult consist of 32 distinct
teeth, 16 in either jaw; being, in fact, a double set. The teeth are
divided into 4 incisors, 2 canine, 4 first and second grinders, and 6
molars; but in childhood the complement or first set consists of only
twenty, and these only make their appearance as the development of the
frame indicates the requirement of a different kind of food for the
support of the system. At birth some of the first-cut teeth are found in
the cavities of the jaw, in a very small and rudimentary form; but this
is by no means universal. About the third month, the jaws, which are
hollow and divided into separate cells, begin to expand, making room for
the slowly developing teeth, which, arranged for beauty and economy of
space lengthwise, gradually turn their tops upwards, piercing the gum by
their edges, which, being sharp, assist in cutting a passage through the
soft parts. There is no particular period at which children cut their
teeth, some being remarkably early, and others equally late. The
earliest age that we have ever ourselves known as a reliable fact was,
_six weeks_. Such peculiarities are generally hereditary, and, as in
this case, common to a whole family. The two extremes are probably
represented by six and sixteen months. Pain and drivelling are the
usual, but by no means the general, indications of teething.

2511. About the sixth month the gums become tense and swollen,
presenting a red, shiny appearance, while the salivary glands pour out
an unusual quantity of saliva. After a time, a white line or round spot
is observed on the top of one part of the gums, and the sharp edge of
the tooth may be felt beneath if the finger is gently pressed on the
part. Through these white spots the teeth burst their way in the
following order:--

2512. Two incisors in the lower jaw are first cut, though, in general,
some weeks elapse between the appearance of the first and the advent of
the second. The next teeth cut are the four incisors of the upper jaw.
The next in order are the remaining two incisors of the bottom, one on
each side, then two top and two bottom on