464 THE HUMAN BODY. 



changes causing a sensation of pain. Kevertheless in the 

 one case we speak of the cold as being in the knife, and in 

 the other of the pain as being in the finger. 



Sensitive parts, such as the surface of the skin, through 

 which we get, or believe we get, information about outer 

 things, are of far more intellectual value to us than sensitive 

 parts, such as the subcutaneous tissue into which the knife 

 may cut, which give us only sensations referred to conditions 

 of our Bodies. The former are called Sense-organs proper, 

 or Organs of Special Sense; the latter are sensitive parts, or 

 Organs of Common Sensation. 



The Peripheral Reference of our Sensations. The 

 fact that we refer certain sensations to external causes is 

 only one case of a more general law, in accordance with 

 which we do not ascribe our sensations, as regards their lo- 

 cality, to the brain, where the neurosis is accompanied by 

 the sensation, but to a peripheral part. With respect to 

 the brain, other parts of the Body are external objects as 

 much as the rest of the material universe, yet we locate the 

 majority of our common sensations at the places where the 

 sensory nerves concerned are irritated, and not in the brain. 

 Even if a nerve-trunk be stimulated in the middle of its 

 course, we refer the resulting sensation to its outer endings. 

 A blow on the inside of the elbow-joint, injuring the ulnar 

 nerve, produces not only a local pain, but a sense of ting- 

 ling ascribed to the fingers to which the ends of the fibres 

 go. Persons with amputated limbs have feelings in their 

 fingers and toes long after they have been lost, if the nerve- 

 trunks in the stump be irritated. To explain such facts we 

 must trench on the ground of Psychology, and so they can- 

 not be fully discussed here; but they are commonly ascribed 

 to the rggults of experience. The events of life have taught 

 us that in the great majority of instances the sensory im- 

 pulses which excite a given tactile sensation, for example, 

 have acted upon the tip of a finger. The sensation goes when 

 the finger is removed, and returns when it is replaced; and 

 the eye confirms the contact of the external object with the 

 finger-tip when we get the tactile sensation in question. 

 We thus come firmly to associate a particular region of the 



