tion, therefore, to a guest to wash his hands before dinner is
really an invitation for him to disinfect himself or to get rid of the
germs which he is carrying, in order that the host and his family may
not be infected during the meal. The guest owes it to his host always to
accept the invitation, whether he thinks he needs it or not. Doctors
recognize the necessity, and it is surprising to observe how many times
during the day a doctor washes his hands, even though he may not come in
contact with any particularly infectious disease. An ordinary man, on
the other hand, washes his hands only when he thinks they are dirty,
although his daily occupation may expose the skin of his hands to
infection many times worse than that which the doctor experiences.

_Mouth breathing._

Children have sometimes wondered why they were made with both mouths and
noses, since they could breathe equally with either, and many years
have gone by before they realized that breathing through the mouth was
not intended, but that the exclusive province of the nose was to furnish
air to the lungs. The reason for nose breathing rather than mouth
breathing is twofold. In the first place, no provision for removing or
filtering out germs from the air is made in the mouth, whereas in the
nose the crooked passages, the moist surfaces, and the hairlike growths
all tend to strain out any germs normally in the inspired air.

Further, breathing through the mouth has a tendency to induce
inflammation in the tonsils and in the air passage connecting with the
ear. This inflammation develops into those growths known as adenoids,
which, when enlarged sufficiently, close the nostril entirely and
prevent its normal use. A recent examination made by the New York Board
of Health of 150 school children, all in some way abnormal, showed that
137 had either adenoids or enlarged tonsils. Example after example could
be given of school boys and girls whose mental and moral development has
been markedly retarded because of mouth breathing. One need only look at
a child or adult who constantly keeps his or her mouth open to be
impressed by the listless, vacant, inert appearance of the face thus
disfigured. Figure 74 shows a photograph of a schoolgirl just before an
operation and the characteristic expression due to adenoids is plainly
marked. Earache is largely due to adenoids or to inflammation that
rapidly leads to adenoids, and Mr. William H. Allen, Secretary of the
Bu