the old elephant trumpet much more loudly, and invariably both the
upper and lower orbicular muscles were strongly contracted, and now in
an equal degree. It is a singular fact that the African elephant,
which, however, is so different from the Indian species that it is
placed by some naturalists in a distinct sub-genus, when made on two
occasions to trumpet loudly, exhibited no trace of the contraction of
the orbicular muscles.
From the several foregoing cases with respect to Man, there can, I
think, be no doubt that the contraction of the muscles round the eyes,
during violent expiration or when the expanded chest is forcibly
compressed, is, in some manner, intimately connected with the secretion
of tears. This holds good under widely different emotions, and
independently of any emotion. It is not, of course, meant that tears
cannot be secreted without the contraction of these muscles; for it is
notorious that they are often freely shed with the eyelids not closed,
and with the brows unwrinkled. The contraction must be both involuntary
and prolonged, as during a choking fit, or energetic, as during a
sneeze. The mere involuntary winking of the eyelids, though often
repeated, does not bring tears into the eyes. Nor does the voluntary
and prolonged contraction of the several surrounding muscles suffice.
As the lacrymal glands of children are easily excited, I persuaded my
own and several other children of different ages to contract these
muscles repeatedly with their utmost force, and to continue doing so as
long as they possibly could; but this produced hardly any effect. There
was sometimes a little moisture in the eyes, but not more than
apparently could be accounted for by the squeezing out of the already
secreted tears within the glands.
The nature of the relation between the involuntary and energetic
contraction of the muscles round the eyes, and the secretion of tears,
cannot be positively ascertained, but a probable view may be suggested.
The primary function of the secretion of tears, together with some
mucus, is to lubricate the surface of the eye; and a secondary one, as
some believe, is to keep the nostrils damp, so that the inhaled air may
be moist,[621] and likewise to favour the power of smelling. But
another, and at least equally important function of tears, is to wash
out particles of dust or other minute objects which may get into the
eyes. That this is of great importance is clear from the cases in which
the cornea has been rendered opaque through inflammation, caused by
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