CHAPTER VI
NATURAL SELECTION AND ENVIRONMENT
I have attempted to show that animal development has not been an
aimless drifting. Functions developed and organs arose and were
perfected in a certain order. First the purely vegetative organs
appeared, and the animal lived for digestion and reproduction; then
came muscle and it brought with it nerve. But these were not enough;
the brain had all the time been gradually improving, and now it
becomes the dominant function to which all others are subordinated.
The experiment was fairly tried. Mere digestion and reproduction are
carried to about the highest perfection which can be expected of
them in worms and mollusks. The bird tried what could be done with
digestion ministering to locomotion guided by the very keenest
sense-organs and controlled by no mean brain. Even this experiment
was not a success. But one organ remained, the brain, and on its
mental possibilities depend the future of the animal kingdom.
Vegetative organs and muscle have been tried and found wanting.[1]
[Footnote 1: See chart, p. 310.]
We have followed hastily the development of mind. The mind began its
career as the servant of digestion, recognizing and aiding to attain
food. Action is at first mainly reflex. But conscious perception
plays an ever more important part.
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