_When is this habit most frequently seen?_

It begins in quite early infancy, and if not broken may last until
children are six or seven years old.

_Is the sucking habit a harmful one?_

When persisted in it may produce a misshapen mouth or fingers. It
constantly stimulates the flow of saliva and certainly aggravates
disturbances of digestion during which the sucking habit is likely to
be practised. It may lead to thrush or other forms of infection of the
mouth. It is not necessary as a means of quieting a child, though it
may in some degree cover up the consequences of bad feeding or bad
training. On no account should the habit of sucking the "pacifier" be
allowed as a means of putting children to sleep, or of quieting them
while restless from dentition or indigestion.

_How is the sucking habit to be controlled?_

One should be sure in the first place that the constant sucking of
fingers is not due to hunger from insufficient food. Sucking of the
hands may often be controlled by wearing mittens or fastening the
hands to the sides during sleep. In more obstinate cases it may be
necessary to confine the elbow by small pasteboard splints to prevent
the child from bending the arm so as to get the hand to the mouth.

_When are nail-biting and dirt-eating seen, and how are they to be
controlled?_

These habits belong especially to children over three years old. They