The reason why : $b a careful collection of many hundreds of reasons for things which, though generally believed, are imperfectly understood. A book of condensed scientific knowledge for the million
John Stuart Mill · en
Because, in a wild state, they are constantly exposed to the attacks
of carnivorous beasts, and as the mastication of the large amount of
vegetable food required for their sustenance would take a considerable
time, they are provided with stomachs, by which they are enabled to
fill their paunches quickly, and then, retiring to a place of safety,
they bring their food up again, and chew it at leisure.
[Verse: "A righteous man regardeth the life of his beast: but the
tender mercies of the wicked are cruel."--PROVERBS XII.]
1089. _Why can ruminating animals recover the food from their paunches?_
Because they have a _voluntary power_ over the muscles of the throat,
by which they can bring up the food at will.
1090. _Why can they keep the unchewed food in the paunch, from the
"cud" they have chewed for nourishment?_
Because their stomachs are divided into three chambers: 1, the
_paunch,_ where the unchewed food is stored; 2, the _reticulum_, where
portions of the food are received from the paunch, and moistened and
rolled into a "cud," to be sent up and chewed; and 3, the _psalterium_,
which receives the masticated food, and continues the process of
digestion.
In quadrupeds the deficiency of teeth is usually _compensated_
by the faculty of rumination. The sheep, deer, and ox tribe, are
without fore-teeth in the upper jaw. These ruminate. The horse
and ass are furnished with teeth in the upper jaw, and do not
ruminate. In the former class, the grass and hay descend into the
stomachs nearly in the state in which they are cropped from the
pasture, or gathered from the bundle. In the stomach, they are
softened by the gastric juice, which in these animals is unusually
copious. Thus softened and rendered tender, they are returned a
second time to the action of the mouth, where the grinding teeth
complete at their leisure the trituration which is necessary;
but which was before left imperfect. I say, the trituration
which is necessary; for it appears from experiments, that the
gastric fluid of sheep, for example, has no effect in digesting
plants, unless they have been previously masticated; that it only
produces a slight maceration, nearly as common water would do in
a like degree of heat; but that when once vegetables are reduced
to pieces by mastication, the fluid then exerts upon them its
specific operation. Its first effect is to soften them, and to
destroy their natural consistency; it then goes on to dissolve
them, not sparing even the toughest parts, such as the nerves of
the leaves. I think it very probable, that the gratification also
of the animal is renewed and prolonged by this faculty. Sheep,
deer, and oxen, appear to be in a state of enjoyment whilst they
are chewing the cud. It is then, perhaps, that they best relish
their food.--_Paley._