7rcTIX1xP

The Eighth Lesson: The Ascent of Man.825
The Eighth Lesson: The Ascent of Man.
I
n our last lesson we led you by successive steps from the beginnings of
Life in living forms up to the creatures closely resembling the family of
vertebrates—the highest family of living forms on this planet. In this present
lesson we take up the story of the “Ascent of Man” from the lowly vertebrate
forms.
The large sub-family of forms called “The Vertebrates” are distinguished
from the Invertebrates by reason of the former possessing an internal bony
skeleton, the most important feature of which is the vertebra or spinal
column. The vertebrates, be it remembered, possess practically the same
organs as the lower forms of life, but differ from them most materially by
the possession of the internal skeleton, the lower forms having an external
or outside skeleton, which latter is merely a hardening of the skin.
The flexibility of the vertebra creates a wonderful strength of structure,
combined with an ease of movement peculiar to the vertebrates, and which
renders them the natural forms of life capable of rapid development and
evolution. By means of this strength, and ease, these forms are enabled to
move rapidly in pursuit of their prey, and away from their pursuers, and
also to resist outside pressure or attack. They are protected in a way similar
to the invertebrates having shells, and yet have the additional advantage