96 



ANN HAVEN MORGAN 



Independence of the responses to touch and heat. In the human 

 skin responses to tactile stimulations occur quickly, but pain and 

 heat have a longer reaction interval. In the frog reaction times 

 to touch and heat were first compared in the normal skin as a 

 step toward the separation of the two senses and finally from 

 those of cold, pain, and the chemical senses. 



In these comparative experiments the heat stimulation was 

 conducted as before. In applying the tactile stimulus a simple 



TABLE 6 

 Responses in seconds to heat at 40°C. and to heat increasing by 5°C. at each stimu- 

 lation in a range of 25°C. to 50°C. Left foot with skin removed. Right foot 

 normal. Reaction allowa^ice, SO seconds. Stimulation time, 2 minutes, co = 

 no response 



device was employed by which the stimulus could be kept imi- 

 form and brought to bear on a particular area (fig. 1). This 

 device consisted of a single iron standard from the top of which the 

 frog was suspended by an adjustable arm. Below this were two 

 adjustable arms also provided with clamps. Into the lower and 

 longer one a small board was fastened by a flexible wire so that 

 the board could be easily turned in any direction. This board 

 served to support the frog's foot very lightly and when flooded 

 with water there was probably little tactile stimulation from it. 



