But the resources for mischief of this pharyngeal "Old Man of the Sea"
are not even yet exhausted. Next comes a very curious and unexpected
one. We have all heard much of "the struggle for existence" among plants
and animals, and have had painful demonstrations of its reality in our
own personal experience. But we hardly suspected that it was going on in
our own interior. Such, however, is the case; and when once one organ or
structure falls behind the others in the race of growth, its neighbors
promptly begin to encroach upon and take advantage of it. Emerson was
right when he said, "I am the Cosmos," the universe.
Now, the mouth and the nose were originally one cavity. As Huxley long
ago remarked, "When Nature undertook to build the skull of a land animal
she was too lazy to start on new lines, and simply took the old
fish-skull and made it over, for air-breathing purposes." And a clumsy
job she made of it!
It may be remarked, in passing, that mouth-breathing, as a matter of
history, is an exceedingly old and respectable habit, a reversion, in
fact, to the method of breathing of the fish and the frog. "To drink
like a fish" is a shameful and utterly unfounded aspersion upon a
blameless creature of most correct habits and model deportment. What the
poor goldfish in the bowl is really doing with his continual "gulp,
gulp!" is breathing--not drinking.
This remodeling starts at a very early period of our individual
existence. A horizontal ridge begins to grow out on either side of our
mouth-nose cavity, just above the roots of the teeth. This thickens and
widens into a pair of shelves, which finally, about the third month of
embryonic life, meet in the middle line to form the hard palate or roof
of the mouth, which forms also the floor of the nose. Failure of the two
shelves to meet properly causes the well-known "cleft-palate," and, if
this failure extends forward to the jaw, "hare-lip." In the growth of a
healthy child a balance is preserved between these lower and upper
compartments of the original mouth-nose cavity, and the nose above
growing as rapidly in depth and in breadth as the mouth below, the
horizontal partition between--the floor of the nose and the roof of the
mouth--is kept comparatively flat and level. In adenoids, however, the
nostrils no longer being adequately used, and consequently failing to
grow, and the mouth cavity below growing at the full normal rate, it is
not long before the mouth begins to encroach upon the nostrils by
pushing up the partition of the palate. As soon as this upward bulge of
the roof of the mouth occurs, then there is a diminution of the
resistance offered by the horizontal healthy palate to the continual
pressure of the muscles of the cheeks and of mastication upon the sides
of the upper jaw, the more readily as the tongue has dropped down from
its proper resting position up in the roof of the mouth. These are
pushed inward, the arch of the jaw and of the teeth is narrowed, the
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