354 



ELEMENTARY PHYSIOLOGY 



(iii) The Sensation of Pain. — Pain may be regarded 

 as the result of an excessive stimulation of any of the 

 nerve endings which are concerned in giving rise to 

 sensations. Pain also results from stimulating the trunks 

 of the nerves leading from those endings to the central 



Pio. 112.— Outlines of Heat Spots and Cold Spots. (After 



GOLD.SCHEIDEK.) 



Tlie heat spots are cross-liatched and dark, the cold spots are dotted 

 and light. In some places the heat spots and cold spots overlap each 

 other. 



nervous system. In the latter case the"[^)ain is "referred " 

 outwards to the end of the nerve, as in the experiment of 

 cooling the elbow, described above. The nerves of any 

 part may thus give rise to pain. From this it might 

 appear that we can scarcely speak of any distinct and 



