An introduction to the study of mammals living and extinctLydekker, Richard
Science
An introduction to the study of mammals living and extinct
Lydekker, Richard
Mammals
in the cheek, just under cover of the anterior part of the zygomatic
arch, its duct entering the buccal cavity near that of the parotid.
The most obvious function common to the secretion of these various
glands, and to that of the smaller ones placed in the mucous membrane
of the lips, the cheeks, the tongue, the palate, and fauces, is the
mechanical one of moistening and softening the food, to enable it the
more readily to be tasted, masticated, and swallowed, though each kind of
gland may contribute in different manner and different degree to perform
this function. The saliva is, moreover, of the greatest importance in the
first stage or introduction to the digestive process, as it dissolves
or makes a watery extract of all soluble substances in the food, and
so prepares them to be further acted on by the more potent digestive
fluids met with subsequently in their progress through the alimentary
canal. In addition to these functions it seems now well established by
experiment that saliva serves in Man and many animals to aid directly
in the digestive process, particularly by its power of inducing the
saccharine transformation of amylaceous substances. As a general rule,
in mammals the parotid saliva is more watery in its composition, while
that of the submaxillaries, and still more the sublingual, contains
more solid elements and is more viscid;—so much so that some anatomists
consider the latter, together with the small racemose glands of the
cheeks, lips, and tongue, as mucous glands, retaining the name of
salivary only for the parotid. These peculiar properties are sometimes
illustrated in a remarkable degree, as, for example, the great secretion
of excessively viscid saliva which lubricates the tongue of the Anteaters
and Armadillos, associated with enormously developed submaxillary glands;
while, on the other hand, the parotids are of great size in those animals
which habitually masticate dry and fibrous food.
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