106 



ANN HAVEN MORGAN 



By previous tests the skin had been unresponsive to 25°C. 

 Tests with decreasing cold were begun at this degree therefore 

 and the temperature was decreased with intervals of 5° down to 

 1°C. The right feet were desensitized in order to further demon- 

 strate the possibility of eliminating the cold sense from the skin. 

 The right and left foot were alternately stimulated but, except 



TABLE 15 



Responses of foot to water at 2°C. Right foot cocained 30 minutes. Reaction 



alloivance, 30 seconds. Stimulation time, 2 minutes 



in one case, there was no response till the temperature was reduced 

 to 10°C. (table 16). 



Between 35°C. to 43°C. and 10°C. to 15°C. there was a range 

 of temperature to which the frog's skin did not respond. This 

 range was limited on one side by the threshhold stimulus for 

 heat and on the other by that for cold. The cold as well as the 

 heat receptors have been proved to lie in the skin. The response 

 to cold has its own peculiar characteristics, also a shorter reac- 

 tion time and an earher exhaustion point. 



