block the air passages and give rise
to mouth-breathing and its attendant disorders.

Another cause of mouth-breathing is extreme swelling of the membrane
which covers the turbinated bones of the nose.]

=COLD IN THE HEAD FROM OVERHEATING.=--Chilling of the surface of the
body favors the occurrence of colds, in which lowered bodily vitality
allows the growth of certain germs always present upon the mucous
membrane lining the cavities of the nose. Dust and irritating vapors
also predispose to colds. Overwarm clothing makes a person susceptible
to colds, while the daily use of cold baths is an effective
preventive. There is no sufficient reason for dressing more warmly in
a heated house in winter than one would dress in summer. It is,
moreover, unwise to cover the chest more heavily than the rest of the
body. Some one has wisely said: "The best place for a chest protector
is on the soles of the feet." The rule should always be to keep the
feet dry and warm, and adapt the clothing to the surrounding
temperature. Among the germs which cause colds in the head, that of
pneumonia is the one commonly found in the discharge from the nose.
When pneumonia is epidemic it is therefore wise to take extra
precautions to avoid colds, and care for them when they occur.

The presence of chronic trouble in the throat and nose, such as
described under Mouth-Breathing, Adenoids, etc. (p. 60), is perhaps
the most frequent cause of colds, because the natural resistance of
the healthy mucous membrane to the attack of germs is diminished
thereby, and the catarrhal secretions form a source of food for the
germs to grow upon. It should also be kept in mind that cold in the
head is the first sign of measles and of _grippe_. Colds are more
common in the spring and fall.

=Symptoms.=--Colds begin with chilliness and sneezing, and, if severe,
there may be also headache, fever, and pain in the back and limbs, as
in _grippe_. The nose at first feels dry, but soon becomes more or
less stopped with secretion. The catarrh may extend from the back of
the nose through the Eustachian tube to the ear, causing earache,
noises in the ear, and deafness (see p. 41). This unfortunate result
may be averted by proper spraying of the nose, and avoidance of
blowing the nose violently.

=Treatment.=--Treatment must be begun at the first suspicion of an
attack to be of much service. The bowels should be opened with calomel
or other cathartic; two-fifths of a gra