THERMAL SENSATIONS 



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FIG. 20. Records showing the warm fiber response to sudden heating and cooling of the cat tongue 

 at different levels. .4, temperature rise, 14.2° to 38.6°C, latency 0.55 sec. B, 25.3° to 38.6°C, latency 

 0.46 sec. C, 30° to 38.6°C, latency 0.42 sec. D, 34.4° to 38.6°C, latency 0.47 sec. The latency of the 

 off-effect, 'paradoxical warmth,' varied between o.io and 0.15 sec. [From Dodt & Zotterman (23).] 



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FIG. 21. Simultaneous recording from a warm fiber preparation of the chorda tympani and a 

 cold fiber preparation of the lingual nerve. A and B, a rise from 23° to 38.5°C and back; C and D, 

 from 23.8° to 44.8°C and back. B and D are recorded 6 sec. after the previous record. [From Dodt 

 & Zotterman (23).] 



Strong off-discharge from the warm fibers. As can be 

 seen in figure 21, this effect occurred after a very short 

 latency, much shorter even than that of the cold fiber 

 discharge. When the heating was repeated within 6 

 sec, the initial warm fiber response to heating to 

 44.8°C each time was very much reduced while the 



off-effect from the warm fibers remained almost 

 unchanged. 



This off-effect of the warm fibers was observed 

 whenever the temperature dropped about 8° to 

 I5°C. It is more conspicuous the more rapid the 

 change in temperature, but it appeared even at 



