CONTACT CEPTORS 81 



those animals which hibernate prolonged cold means a 

 period of lessened food supply. 



The response to external heat by sweating and mus- 

 cular relaxation is an effective method for reducing heat 

 production and increasing heat elimination. 



The Specific Response of Pain 



In addition to these various protective mechanisms, 

 there exists for the defense of the body the important 

 phenomenon of pain. The pain which accompanies ab- 

 normal organic conditions will be considered in other 

 parts of this volume, but the pain which forms part of 

 the response to excessive light, to heat, to cold, to me- 

 chanical injury, to local anemia resulting from a cramped 

 position, or to the pressure upon internal organs which 

 presages the evacuation of their contents, is essentially a 

 normal phenomenon and must be considered with other 

 normal adaptations initiated by the stimulation of 

 contact ceptors. 



In type, location and intensity pain is always specific 

 to the stimulus by which it is evoked. In addition pain 

 is always associated with some form of muscular action 

 by which the body moves away from, fights off, re- 

 moves or expels from the body harmful agents or prod- 

 ucts or makes other muscular adjustments and adapta- 

 tions. As we shall see later, pain is analogous in nature 

 to the phenomena of the emotions which occur in re- 

 sponse to distance ceptor stimulation and in an analo- 

 gous manner expedite adaptive motor reactions. 



A child puts his hand into the fire, and instantly re- 

 coils. A boy steps upon a sharp stone, and bounds 

 away hastily. Pain is the precursor of each act. Pro- 



