FIG. 6.

[Illustration: _The Spine; the seven vertebre of the neck, cervical; the
twelve of the back, dorsal; the five of the loins, lumbar;_ a, _the
sacrum, and_ b, _the coccyx, coming the nine "false vertebre."_
(p. 3).]

2 THE TRUNK.

THE TRUNK has two important cavities. The upper part, or _chest_,
contains the heart and the lungs, and the lower part, or _abdomen_,
holds the stomach, liver, kidneys, and other organs (Fig. 31). The
principal bones are those of the _spine_, the _ribs_, and the
_hips_.

THE SPINE consists of twenty-four bones, between which are placed pads of
cartilage. [Footnote: These pads vary in thickness from one fourth to one
half an inch. They become condensed by the weight they bear during the
day, so that we are somewhat shorter at evening than in the morning.
Their elasticity causes them to resume their usual size during the night,
or when we lie down for a time.] A canal is hollowed out of the column
for the safe passage of the spinal cord. (See Fig. 50.) Projections
(processes) at the back and on either side are abundant for the attachment
of the muscles. The packing acts as a cushion to prevent any jar from
reaching the brain when we jump or run, while the double curve of the
spine also tends to disperse the force of a fall. Thus on every side the
utmost caution is taken to guard that precious gem in its casket.

THE PERFECTION OF THE SPINE surpasses all human contrivances. Its various
uses seem a bundle of contradictions. A chain of twenty-four bones is made