ood of an appropriate quality,
taken in proper quantities, at regular periods, and also properly
masticated.

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330. Give the summary when digestion is most perfect.

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CHAPTER VXII.

THE CIRCULATORY ORGANS.

331. The ultimate object of the food and drink introduced into the
body, is to furnish material to promote the growth and repair the
waste of the organs of the system. The formation of chyle (the
nutrient portion of the food) has been traced through the digestive
process, and its transfer into the vein at the lower part of the neck,
from which it is conveyed to the heart; and, finally, in the lungs it
assimilates to the character of blood.

332. The BLOOD, after standing a short time, when drawn from its
vessels, separates into _se'rum_, (a watery fluid,) and _co-ag'u-lum_,
(clot.) This fluid is distributed to every part of the system. There
is no part so minute that it does not receive blood. The organs by
which this distribution is effected are so connected that there is
properly neither beginning nor end; but as it respects their
functions, they are connected in a complete circle. From this
circumstance, they are called the _Circulatory Organs_.

ANATOMY OF THE CIRCULATORY ORGANS.

333. The CIRCULATORY ORGANS are the _Heart_, _Ar'te-ries_, _Veins_,
and _Cap'il-la-ries_.

334. The HEART is placed obliquely, in the left cavity of the chest,
between the right and left lung. Its general form is that of an
inverted cone, the base of which is directed upward and backward,
toward the right shoulder, while its apex points forward to the left
side, about three inches from the sternum to the space between the
fifth and sixth ribs. Its under side rests upon the tendinous portion
of the diaphragm. The heart is surrounded by a sac, called the
_per-i-car'di-um_, (heart-case.) The interior surface of this membrane
secretes a watery fluid, that lubricates the exterior of the heart,
and obviates friction between it and the pericardium.

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331. what is the ultimate object of the food? 332. Of what is the
blood composed? What is said of the distribution of the blood? 333.
Name the circulatory organs. 334-351. _Give the anatomy of the
circulatory organs._ 334. Describe the heart.

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[Illustration: Fig. 66. A front view of the heart. 1, The right auricle
of the heart. 2, The left auricle. 3, The right