We have now the beginning of an explanation of the element of design in the movements of animals. But, first, the explanation is necessary to account for the long-continued automatic acts which have
Fig. 9.—Cast of Brain-Cavity of P ocamelus occidentalis, one half natural size: a, profile; b, above; c, below. (Prom New Mexico.) changed the hard and apparently fixed structures of so many of the higher forms of life.
Automatic and unconscious ratiocinative acts are the product of conscious ratiocinative acts by the process of cryptonoÿ already referred to. This process is one of the most wonderful which the field of science presents to our contemplation. It is simply this: that when a brain, or other organ of consciousness, has once acquired an habitual movement, consciousness disappears from that act, and it enters the unconscious and generally automatic stage. This demonstrates two things: First, that consciousness is not necessary to a designed act which has become a habit, no matter how complicated that habit may be; second, that consciousness does reside in matter which has not acquired habits, and which therefore does not yet possess the structure which makes such habits possible.
We now have a true theory of the influence of the environment on an animal. Sensation being understood, the animal proceeds to adapt itself to its surroundings by the adoption of appropriate habits, from which appropriate structures arise. Without such response on the part of the animal, the greater part of the world would have remained uninhabited by all but the lowest forms of life, and these too might have been extinguished. From the simplest temporary methods of defense and protection, animals have developed the habits of laying up stores, of building houses, of the arts of the chase, of migrations over wide territories. There can be no doubt that the constant exercise of the mind in self-support and protection has developed the most wonderful of all machines, the human brain, whose function is the most
