EVOLUTION OF NERVOUS SYSTEM 83 



ties. Persons who have recently lost an arm or a leg often 

 suffer from very intense pains apparently in the missing part. 

 So real are these sensations and so definitely do they seem to 

 be located in the lost member that it is often difficult to per- 

 suade the patient that the pains are not connected with the lost 

 part and that some attention to that part is needed. Yet the 

 surgeon knows perfectly well that these sensations are caused 

 by small tumors on the cut ends of the nerves that formerly 

 went to the lost extremity. On removing these tumors the 

 sensations disappear. Both these lines of evidence show that 

 painful sensations though commonly referred to the skin are 

 really not situated there. They are functions of a more 

 deeply located part. When the central end of the system in 

 the cerebral cortex suffers destruction either by disease or acci- 

 dent, sensation disappears absolutely and completely, a condi- 

 tion that shows that the real seat of this phenomenon is not in 

 the peripheral parts of the body, as commonly assumed, but in 

 a deep portion of the central nervous system. 



This is but one example of many that go to show that per- 

 sonality, not only from its sensational side but from all other 

 aspects of its nature, is a function of the nervous system. It 

 is not a quality that penetrates the human frame as a whole. 

 Yet notwithstanding the correctness of the modern view as 

 to the seat of personality, the ancient idea of its diffuse nature 

 appears in many of our daily habits and permeates our lan- 

 guage. It would be impossible to replace successfully the 

 heart on the February valentine by the true organ of affection, 

 the cerebral cortex, even though the convolutions of the cortex 

 might be shown to afford a much more subtile means of send- 

 ing the hidden message than the smooth surface of the heart. 

 Human nature clings to the past and the discarded theories of 

 the physicians of antiquity hold their place with tenacity in the 

 language of to-day. 



