ii SENSIBILITY OF THE INTERNAL ORGANS 67 



are often felt, but these are not so much true pain as an obscure 

 feeling of heaviness or strain, while true, sharp, stabbing pain is 

 projected to the surface of the body. According to Head, this 

 false localisation is an effect of the low sensibility to pain of the 

 internal organs and tissues, and of the connection between these 



Fio. 26. Diagram of zones and areas of hyperalgesia, after the clinical researches of Head. 

 Explanation on p. 68. 



and the nerve-centres of the much more sensitive external tissues. 

 Head's law of the localisation of pain runs as follows : 



" When a painful stimulus is applied to a part of low sensi- 

 bility in close central connection with a part of much greater 

 sensibility, the pain produced is felt in the part of higher sensi- 

 bility rather than in the part of lower sensibility to which the 

 stimulus was actually applied." l 



1 Brain, 1893, vol. xvi. p. 127. 



