390 THE OUTGO OF ENERGY 



THE SKIN 

 SENSATIONS OF TEMPERATURE 



Hot and Cold Spots. With a lead-pencil point 

 carefully explore an area about an inch square 

 on the back of the wrist or hand. Mark with 

 black ink the places where a distinct sensation of 

 cold is felt, and with red ink those where the 

 sensation is one of warmth. 



The places indicated are the so-called hot and 

 cold spots. 



Outline. Attempt to define more exactly the 

 outline of one of the cold spots. 



The spots are of irregular shape, blotches 

 rather than points. 



Mechanical Stimulation. 1. Gently tap one 

 end of a small wooden rod the other end of which 

 is placed on a well-defined cold spot. 



The mechanical stimulation of the cold spot 

 will give a sensation of cold. ;.,., 



2. Stimulate a warm spot mechanically. 



Chemical Stimulation. Rub a menthol pencil 

 over a small area on the back of the hand. 



