NERVES. . 461 



derived from the nervous system, a collection of organs one of 

 whose functions is to cause the different organs to act harmo- 

 niously. The effect of a want of harmony under the circumstances 

 just supposed would be most disastrous. If the nervous force 

 was not at command to make the muscles respond when their 

 increased action was desired, there would be a condition of paral- 

 ysis, or if, when the muscles attempted to perform this added task, 

 the heart should fail to respond, the effort would be fruitless ; and 

 equally unavailing would be the attempt if at the crucial moment 

 the lungs and other respiratory organs should be unresponsive. 

 Many other illustrations of the interdependence of the organs 

 might be given, but a little reflection will suggest them almost 

 ad infinitum. 



The simplest movements that are made require for their per- 

 formance the conjoint action of several, often many muscles, and 

 were it not for the exciting and controlling power of the nervous 

 system, instead of the harmony which is everywhere and at all 

 times apparent, there would result the utmost confusion. 



In what has been said thus far reference has been had only to 

 the individual, as if he was alone on the face of the earth and 

 interested only in himself; but there are other human beings with 

 whom he is constantly brought into relation, and a world of other 

 animate objects as well as an infinite amount of inanimate matter. 

 This relationship is also accomplished through the nervous system, 

 principally by means of the special senses. It will, therefore, be 

 seen that the nervous functions are those which bring the different 

 organs of the body into harmonious relations with one another, 

 and, in addition, bring the individual, through the special senses 

 sight, hearing, etc. into relation with the world outside him. 



The nervous system is made up of collections of nervous 

 tissue, which is composed of two kinds of matter nerve-fibers 

 and nerve-cells, with neuroglia ; these have been already de- 

 scribed (p. 63). 



NERVES* 



Nerve-fibers associated together form nerves, and these con- 

 duct impulses from within outward, from without inward or from 

 one nerve-center to another. Whether it is the function of a 

 given nerve to do the one or the other does not depend upon any- 

 thing in the nerve itself, but upon its relations ; and there is every 

 reason to believe that were it possible to separate a nerve from its 

 anatomic connections and attach it to different structures, it would 

 be just as capable of acting in its new relations as it did in the 

 old ; just as a copper wire will carry equally well a current of 

 electricity to ring a bell or to supply a motor or to turn a hand on 

 a dial : The result depends not upon the wire, but upon the 

 mechanism with which it is in connection. 



