Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: CHAPTER III BEHAVIOR—NATIVE AND ACQUIRED Unlearned activities. — The relation that consciousness has to action may perhaps be seen best by a consideration of behavior that is relatively unconscious. All animals are born capable of performing certain activities, and as they grow older the number of these unlearned activities increases. The vital processes of breathing, digestion, and circulation of the blood are present at birth, and continue without any necessity of conscious control. From the outset the child responds to contact with the lips by the sucking movement. These and many other activities that the child performs without having to learn them are clearly the means that nature has taken to insure his survival. Physical basis of unlearned activities. — Since muscles are never active except as stimulated to action by the nervous system, we must look for the explanation of these unlearned activities in the condition of the nervous system. The nervous mechanisms for performing those activities that are present at birth must be there from the beginning, ready to do their work. Nervous mechanisms ready to function are organized sensori-motor arcs. By an organized sensori-motorpath is meant one in which the parts (that is, the neurones) are so thoroughly connected that they work together as a unit. The synapses that form the connections between neurones offer varying degrees of resistance to the neural impulse. If the resistance is great, so that the impulse cannot pass readily from one neurone to another, the sensori-motor arc is to that degree unorganized. In the case of those sensori-motor arcs that are the mechanism for bringing about unlearned activities, on the other hand, the synaptic connections offer little or no resistance to the nervous current, because they are...