abdomen. 1, 1, 1, 1, The muscles of the chest. 2, 2, 2, 2, The ribs. 3,
3, 3, The upper, middle, and lower lobes of the right lung. 4, 4, The
lobes of the left lung. 5, The right ventricle of the heart. 6, The left
ventricle. 7, The right auricle of the heart. 8, The left auricle. 9, The
pulmonary artery. 10, The aorta. 11, The vena cava descendens. 12, The
trachea. 13, The oesophagus. 14, 14, 14, 14, The pleura. 15, 15, 15, The
diaphragm. 16, 16, The right and left lobe of the liver. 17, The
gall-cyst. 18, The stomach. 26, The spleen. 19, 19, The duodenum. 20, The
ascending colon. 21, The transverse colon. 25, The descending colon. 22,
22, 22, 22, The small intestine. 23, 23, The abdominal walls turned down.
24, The thoracic duct, opening into the left subclavian vein, (27.)]

CHAPTER XXIII.

THE RESPIRATORY ORGANS.

463. The nutrient portion of the food is poured into the left
subclavian vein, (24, 27, fig. 88,) at the lower part of the neck, and
is carried to the right cavities of the heart. The fluid in these
cavities consists of the chyle incorporated with the impure blood.
Neither of these two elements is fitted to promote the growth or
repair the waste of the body. They must be subjected to a process, by
which the first can be converted into blood, and the second freed of
its carbonic acid gas and water. This is effected by the _Respiratory
Organs_.

ANATOMY OF THE RESPIRATORY ORGANS.

464. The RESPIRATORY ORGANS are the _Lungs_, (lights,) the _Tra'che-a_,
(windpipe,) the _Bronch'i-a_, (subdivisions of the trachea,) and the
_Air-Ves'i-cles_, (air-cells at the extremities of the bronchia.) The
_Di'a-phragm_, (midriff,) _Ribs_, and several _Muscles_, also aid in the
respiratory process.

465. The LUNGS are conical organs, one on each side of the chest,
embracing the heart, (fig. 88,) and separated from each other by a
membranous partition. The color of the lungs is a pinkish gray,
mottled, and variously marked with black. Each lung is divided into
lobes, by a long and deep fissure, which extends from the posterior
surface of the upper part of the organ, downward and forward, nearly
to the anterior angle of the base. In the right lung, the upper lobe
is subdivided by a second fissure. This lung is larger and shorter
than the left. It has three lobes, while the left has only two.

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463. What fluids are conveyed into the right cavities of the heart?
What is necessary bef