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ANN HAVEN MORGAN 



given to the right foot, but the normal left foot showed either a 

 normal reaction time or one slightly longer than usual. Pricking 

 produced immediate and vigorous response in both the cocamed 

 and normal foot even after a long period. 



Independence of the responses to acid solution and heat. The 

 existence of the common chemical sense in the frog's skin was 

 clearly shown by L. W. Cole ('10) and by Crozier ('16). Cole 

 treated the skin with cocaine and found it sensitive to ammonium 

 chloride after response to pain had wholly disappeared, and by 



TABLE 11 

 Responses in seconds to acid solution and to heat. Acid stimulation by 0.5 per cent 

 HCl solution. Right foot cocained 45 minutes. Left foot normal. Reaction 

 alloivance, SO seconds. Stimulation interval, 2 mimites. co = no response 



similar treatment Crozier secured responses to N/20 formic acid 

 after response to pinching had altogether ceased. 



In the separation of chemical and temperature senses the 

 previous method of comparison was repeated. Water at 40°C. 

 and a solution of one-half of 1 per cent hydrochloric acid were 

 used as stimulants. After forty-five minutes of the cocaine 

 treatment there was no response to heat by the right foot, 

 although its reaction to the acid solution was as prompt and 

 vigorous as in the left. These facts are quite in accord with 

 those observed by Crozier. 



