n practically assured of
the pulsating vitality which is a part of superb health.

It is an interesting fact that the spine is the central and fundamental
structure of all the higher organisms on this earth. In the course of
the evolution of life on this planet there developed from the very
simplest forms of animal organisms two different higher forms of
life--on the one hand the vertebrate animals, possessing an internal
skeleton, and on the other hand the insects, clams, crustaceans and
other creatures that have their skeletons on the outside, as one may
say, in the form of shells. The legs of an insect, for instance, are
small tubes with the muscles inside. The limbs of vertebrate animals,
on the other hand, have the muscle outside the bone. Invertebrates
commonly have the main nerve trunk in front, or underneath, instead of
at the back, and likewise often have their brains in their abdomens.
Some of them, such as the grasshopper, even hear with their
abdomens. But all vertebrata have the great nerve trunk at the back,
contained in the spine and with a bulb on the front or upper end
constituting the brain. In fact, a vertebrate animal is primarily a
living spine, and all other parts of the body are in the nature of
appendages. The limbs, for instance, and in the higher animals the ribs
and other parts of the skeleton, are simply attached to the spine, or
are offshoots from it. In the fishes these limbs take the shape of fins.
In the higher developments of life they assume the form of legs.

All the higher animals, as we know, have evolved from the fishes and
reptiles, and all in common possess a spine which in its
fundamental characteristics is very much the same now as when it was
first evolved. In other words, the spine is a bodily structure as old
as the rock-ribbed hills. It has stood the test of time, and therefore
must be regarded as the most highly perfected mechanical structure in
the body. Its strength combined with its flexibility and its perfect
adjustment as a container for the central nervous system, makes it
perhaps the most wonderful structure in the body outside of the brain
and the spinal cord itself. While other organs and features of the body
have been changed and modified to such an extent in the various
species which have been evolved that they can hardly be recognized as
having a common origin, yet the spine has remained substantially the
same. It is t