338 PHYSIOLOGY AND HEALTH. 



the wire ends. Whether the bell be rung by some one in 

 the chamber, or by some one touching the wire in its course, 

 or by any jar acting on the bell itself, the same thought is 

 produced in the mind of the servant whose business it is to 

 watch them. In like manner, whether the impression be first 

 received at the outer termination of the nerve in the organs 

 of sense, or in the flesh, or on its trunk, or at its inner ter- 

 mination in the brain, the same sensation is excited of sound 

 in the ear, sight in the eye, or feeling in the flesh. 



774. These false sensations are created in some diseases. 

 The insane sometimes have false hearing and vision. They 

 seem to hear tke sounds of voices, and even articulated lan- 

 guage. When the imagination is highly stimulated, one sees 

 visions. The timid see frightful apparitions, which seem to 

 assume as distinct a form and color as the real objects of day. 

 Sometimes false vision and false hearing exist together in the 

 same person. He not only sees the form of the object, but 

 he hears the sound of the voice. Men, when suffering from 

 delirium tremens, are troubled with these false sensations. 

 They are often frightened by the voices of spirits or the sight 

 of enemies. The error in these cases is not in the eye, nor 

 in the ear, but in the brain itself. The disease which disturbs 

 this organ produces the same sensations in it that would be 

 produced if the impressions were first made on the eye or ear, 

 and then conveyed by the nerve to the brain. 



775. Communication is very rapid through the nerves 

 so rapid as often to seem to be instantaneous. If we tread 

 upon a thorn, or a heated iron, the sensory nerve conveys the 

 impression to the brain ; this organ recognizes the impression, 

 and then directs that the muscles of the limb lift the foot out 

 of danger, and sends this mandate through the nerve of mo- 

 tion. These two processes the passage of the painful im- 

 pression from the foot to the brain, and of the volition from 

 the brain to the muscle of the foot seem to be simultane- 

 ous, yet they are successive. 



776. Some of the organs of the animal body the hands, 

 the legs, neck, &,c. are subject to the exclusive control of 



