232 'Journal of Comparative Neurology and Psychology. 



by the use of vertical lines. In only a small portion of the third 

 finger does the area of insensitivity to pressure go beyond that of 

 insensitivity to cold. Fig. 7 gives in a similar way the area insens- 

 itive to hot stimuli. For compatison, with the areal loss of cold 

 and hot sensations, the area insensitive to light touch is drawn. On 

 the back of the hand and on the index finger the area of insensibility 

 to light touch is greater than that to heat, while on the thumb the 

 area for hot sensation loss is greater than for light touch. With 

 the exception of a very slight portion of the thumb the area in- 

 sensitive to cold is included within that insensitive to light touch. 

 In a general way, therefore, these results, as has already been 



Fig. 7. 

 Fig. 7. — Area insensitive to liot stimuli, compared witli loss of sensations 

 to light touch. Area insensitive to hot stimuli inclosed within heavy lines. 

 Area marl<ed with horizontal lines insensitive to light touches (cotton wool 

 and camel hair brush). 



said, confirm the obsen^ations of Head. The facts that do not agree 

 with those of Head are : There are different extents of areas respond- 

 ing to different degrees of temperature ; the area for the appreciation 

 of hot stimuli, for example, not being the same as that for the ap- 

 preciation of cold stimuli as such ; temperatures of extreme degree 

 are felt like medium temperatures or call forth sensations of warm- 

 ness or coolness on areas which do not respond to the medium tem- 

 peratures with a corresponding sensation of warmth or coolness. 



The results obtained from the arm may be taken to mean that 

 whenever a cold or hot stimulus was given there was a radiation of 

 effect from the stimulated area to the neighboring areas. This 



