,592 A TEXTBOOK OF PHYSlOLOCV 



of to 24 C. as cold; but no sensations of warmth or coolness 

 were experienced from water at intermediate temperatures. The 

 areas where these sensations were experienced corresponded to hot 

 and cold spots previously marked out. 



This kind of sensibility to pain and temperature is termed proto- 

 pathic. Its chief characteristics are its high threshold stimulation 

 value and the fact that it depends upon the existence of specific end- 

 organs. It probably represents a more primitive type of nervous 

 organization. 



After a variable time the skin again became sensitive to light 

 touch, compass-points were discriminated, and varying degrees of 

 temperature appreciated. This more delicate organization is termed 

 the epicritic system. Epicritic sensibility is characterized by low 

 threshold stimulation value. Its re-establishment may depend on 

 the completion of a single regenerative process, rather than on the 

 regeneration of a special system of epicritic nerves. 



The central connections of the conductors associated with these 

 various sensations are dealt with later. 



