PRODUCTION OF SENSATIONS 349 



touch. Test the lips, tongue, tips of fingers, and palm and back of 

 hand, trying different sizes of bristles. Has the degree of sensitiveness 

 any relation to the thickness of the cuticle ? 



To show Perceptive Differences of Different Portions of the Skin. 

 Place the points of a pair of dividers on the back of the hand of one 

 who looks in the opposite direction. Is one point felt or two ? Repeat 

 several times, changing the distance between the points until it is fully 

 determined how near the two points must be placed in order to be felt 

 as one. In like manner test other parts of the body, as the tips of the 

 fingers and the back of the neck. Compare results obtained at differ- 

 ent places. 



To locate Warm and Cold Sensation Spots. Slowly and evenly 

 draw a blunt-pointed piece of metal over the back of the neck. If it be 

 of the same temperature as the skin, only touch sensations will be expe- 

 rienced. If it be a little colder (the temperature of the room) sensations 

 of cold will be felt at certain spots. If slightly warmer than the body, 

 heat sensation spots will be found on other parts of the skin. If the 

 heat and cold sensation spots be marked and tested from day to day 

 they will be found to remain constant as to position. Inference. 



