the division of labor between them must have
been a long and gradual process.

We have every reason to believe that here, as in insects, the head
has been formed by annexation of segments from the rump and the
fusion of their nervous matter with that of the brain. But here,
instead of only three segments, from nine to fourteen have been
fused in the head to furnish the material for the brain. Notochord
and backbone may be the most striking and apparent characteristic of
vertebrates, but their predominant characteristic is brain. On this
system they lavished material, giving it from three to four times as
much as any lower or earlier group had done. They very early set
apart the cerebral lobes to be the commander-in-chief and centre of
control for all other nerve-centres. To this all report, and from it
all directly or indirectly receive orders. It can say to every
other organ in the body, "Starve that I may live." It is the seat of
thought and will. The other portions of the brain report to it what
they have gathered of vision or sound; it explains the vision or
song or parable. It is relieved as far as possible from all lower
and routine work that it may think and remember and govern. The
vertebrate built for mind, not neglecting the body.

Every trait of vertebrates is a promise of a great future. Its
internal skeleton gives it the possibility of large size. This gave
it in time the victory in the struggle with its competitors, as to
whether it should eat or be eaten. It is vigorous and powerful, for
all its organs are at the best. It gives the possibility of later,
on land, becoming warm-blooded, _i.e._, of maintaining a constant
high temperature. It is thus resistant to climate and hardship. In
time its descendants will face the arctic winter as well as the heat
of the tropics.

But it has started on the road which leads to mind. The greater size
is correlated with longer life. The lessons of experience come to it
over and over again, and it can and must learn them. It is the
intelligent, remembering, thinking type. The insect had begun to
peer into the world of invisible and intangible relations, the
vertebrate will some day see them. This much is prophecied in his
very structure. He must be heir to an indefinite future.

* * * * *

You have probably noticed that the vertebrate differs greatly from
all his predecessors. The gulf between him and them is indeed wide
and deep. His