TEMPERATURE SENSES IN FROG S SKIN 



91 



greater than 1°. It will be remembered that some of the early 

 workers (Goltz, '69; Tarchanow, '71, '72) maintained that if heat 

 were increased slowly enough a frog might be subjected to an 

 extreme degree without making responding resistance. No such 

 results were secured in this investigation even when the heat was 

 increased very slowly. A frog's foot was placed in a beaker of 

 water at 2°C., and a stream of warm water allowed to flow into 

 this which brought it up to 45°C. with almost imperceptible 

 slowness. Although care was taken to prevent the foot from 



TABLE 2 



Respo7ises in seconds to heat increasing by 5°C. at each stage of stimulation. Feet 

 normal. Reaction allowance, 80 seconds. Stimulation interval, 2 minutes for 

 nos. 8, 9, 10, and 5 minutes for no. 11. a> = no reaction 



being affected by this stream, the feet were invariably lifted 

 before the heat had reached 4o°C. 



Variations in the stimulation time and in the heat increments 

 were also tried (table 2). Heat was increased by 5°C. at each 

 stimulation and the right and left feet of the frog were dipped at 

 one-, two-, and five-minute intervals. Of nine frogs used only 

 four reacted at a degree lower than that to which the frogs 

 responded which were subjected to 1°C. increases. The results 

 showed the tendency toward the later reaction with gradually 

 applied stimuli, but also suggested that individual idiosyncrasies. 



