Cattle 1853 - Lewis Family Farm

• THE JEJUNUM AND ILIUM. 331
of the heart, where it is mixed with the venous blood returned from
every part. By the power of the heart it is propelled .through the
lungs, where it is purified and vitalized : and having been returned
to this organ it is driven through other vessels all over the frame,
and bestows nutriment and life on every part.
The food, in a state of perfect solution, and under the name of
chyme, is forced on by the muscular coat of the fourth stomach into
the duodenum, where another change immediately commences. The
food is separated into two distinct portions or principles—that
which is nutritive or capable of being imbibed by the lacteals—
white fluid called chyle—and that which is either innutritive, or
which they reject, and which is propelled along the intestines and
finally evacuated.
There has been much dispute as to the manner in which this
separation is effected. The chyme that has been formed by the
agency of the gastric juice may contain in itself a tendency to this
separation, or precipitation of the excrementitious part ; or this may
be effected by some fluid secreted from the mucous coat of the duodenum
; or the bile and the pancreatic juice may be the main
agents in producing the change.
Ten or twelve inches down the duodenum, as may be seen at h,
p. 291, two ducts penetrate the coats of that intestine, and pour
into it the fluid secreted by the pancreas and liver. It would seem
likely, from the distance from the stomach at which these fluids
enter, that some change had already taken place in the contents of
the duodenum, which was to be perfected by means of these auxilia-
ries. The separation or precipitation is more rapidly and effectually
made ; while the bile also has some stimulating effect on the coats
of the stomach, urging the'exhalents and the absorbents, and the
muscles of the intestines, to stronger and more effectual action ; and
the pancreatic juice may dilute the biliary secretion, and shield the
intestine from its occasional too great acrimony.
While, however, the bile is thus acting in promoting healthy di-
gestion, (and no animals afford more frequent illustration of the connection
between the biliary secretion and the digestive process than
cattle do,) the true notion of it is perhaps, that it is an excrementitious
substance, containing properties that would be noxious to the
constitution, but, as in most of the contrivances of nature, the mode
of its evacuation answers another and a salutary purpose.
The duodenum terminates in the jejunum, but there is no assignable
point wbtere the one can be said to terminate and the other
begin.
THE JEJUNUM AND ILEUM.
These intestines, together with the duodenum, the caecum, and a
portion of the colon, will be seen (in the cut p. 330, at figs. 2 and 3,)
a