CUTANEOUS AND INTERNAL SENSATIONS. 



257 



by Goldscheider and in this country by Donaldson. These ob- 

 servers paid attention chiefly to the warm and cold spots. The 

 existence of these spots may be demonstrated easily by anyone 

 upon himself by moving a metallic point gently over the skin. 

 If the point has a temperature below that of the skin it will be 

 noticed that at certain spots it arouses simply a feeling of contact 

 or pressure, while at other spots it gives a distinct sensation of 

 coldness. If, on the other hand, the point is warmer than the 

 skin it will at certain spots give a sensation of warmth. On mark- 



r 



Fig. 112. Representation of the distribution of cold and warm spots on the volar 

 surface of forearm in a space 2 cms. by 4 cms. The red dots represent the cold spots as 

 tested at a temperature of 10 C. The black dots represent the warm spots as tested at a 

 temperature of 41 to 48 C. 



ing the cold and warm spots thus obtained it is found that they 

 occupy different positions on the skin. Elaborate charts have 

 been made of the warm and cold spots on different regions 

 of the skin, the apparatus usually employed being a metal 

 tube through which water of any desired temperature may be 

 circulated. The temperature of the skin, whatever it may be, 

 forms the zero line; any object of a higher temperature stimulates 

 only the warm spots, while one of a lower temperature acts upon 

 the cold spots. The pressure sense and the pain sense are also 

 distributed in a punctiform manner; they have been studied most 

 17 



