INFLUENCE OF NERVOUS SYSTEM ON HEAT PRODUCTION 509 



up. In certain fevers, therefore, there may be supposed to be some inter- 

 ference with the ordinary cutaneous reflex channels by which the usual 

 temperature sensory stimuli in the skin are prevented from producing the 

 reflexes that result in diminished production of heat in the muscles and other 

 tissues. In consequence of this, and in spite of the condition of increased 

 heat of the body, both at the surface and in the deeper tissues, the production 

 of heat goes on at an abnormal rate. It is not certain whether the patho- 

 logical condition is one which stimulates the thermogenic center by means 

 of which the metabolism of the tissues is increased, or whether the normal 

 reflexes which ordinarily inhibit the activity of the center when the tempera- 

 ture rises fail to bring about their usual reactions. The first is the probable 

 explanation of the high fevers of certain toxemias. 



Drugs may markedly interfere with the function of the thermogenic 

 mechanism. For example, in anesthesia for operative purposes the tem- 

 perature of the body falls below the normal unless heat loss is prevented. 

 If too great loss occurs so that the body temperature as measured in the 

 rectum (determined on cats) falls to 25 C., and lower, the heat regulating 

 mechanism ceases to be operative. It does not regain its function without 

 the aid of artificial heat. But recovery of the thermogenic function may 

 be accomplished by artificial aid even after the rectal temperature has fallen 

 to as low as 16 C. 



