ORIGIN OF THE NERVOUS SYSTEM 141 



ment, a response to vibration or to food, but also 

 an inner mechanism by which the food-canal, the 

 breathing-apparatus, and the other internal organs 

 are brought into nervous connection with the outer 

 mechanism of skin and muscle. In other words, we 

 see the outline of that control and perception of the 

 outer world by movement, prehension, and touch, 

 and the satisfaction of the needs of the inner world of 

 hunger, growth, and racial cares, that is roughly in- 

 dicated by the terms central nervous system and 

 visceral nervous system. 



The question may perhaps be asked, Why have 

 animals developed a nervous system ? The answer, 

 so far as we can give it, bears upon the last discussion. 

 Animals move freely and eat solidly. These two facts 

 go together, and have led to an inevitable distinction 

 between the outer locomotor and inner nutritive 

 regions. Now it is clear that, even if no formal nervous 

 system exists, animal movement demands and pos- 

 sesses a directive and controlling influence. Further, 

 as we know, this regulated locomotor mechanism is 

 able to transmit food to the mouth and to inhale water 

 or air, and the body is able to move the food from 

 place to place in satisfaction of its needs. In other 

 words, animals, even the simple, such as polyps, have 

 a virtual nervous control of their organs of movement 

 and of their visceral organs, and a correlation between 

 the two. Movement, then, and solid food have, so far 

 as we can see, been the two factors responsible for 

 creating the need for that control which is simply 



