220 'Journal of Comparative Neurology and Psychology. 



could not make any good comparison with any other known kinds 

 of sensation, for it was different from pressure and was not like 

 the sensations obtained by brushing or plucking the hairs over normal 

 parts. The feeling (or sensation) could not be localized beyond the 

 general (upper or lower) part of the arm. From numerous stimula- 

 tions and repeated experiments the feeling or sensation was found 

 to depend upon the movement of the skin in neighboring regions. 

 When great care was taken not to move the skin in near-by regions, 

 this unusual and ill-defined sensation did not result. Throughout 

 the series of experiments the patient reported that, although he per- 

 ceived the plucking of the hairs, it should be understood that at 

 no time within the area of the diagram did the sensations have the 

 same quality or character as that produced by plucking the hairs 

 on the right arm. How much of this curious sensation difference 

 was due to suggestion and how much to an actual change can not 

 be determined, but it is fair to assume that the patient was ordinarily 

 trustworthy. 



After locating as accurately as possible the area in which the hairs 

 were insensitive to traction, I mapped out the area in which the hairs 

 were sensitive to stimulation with cotton wool. When, on normal 

 parts, the hairs were lightly brushed with cotton wool, the sensation 

 was immediately perceived, and an accurate localization was made 

 of the place where the stimulus was given. ^Mien the hairs are 

 stimulated as they lie, we find that many hairs from widely separated 

 regions may bo stinmlatcd. This is pai'ticularly so if the hairs luip})en 

 to be long and overlap each other to any extent. To determine 

 with some precision the presence or absence of this form of sensibility, 

 I carefully lifted the hairs overlapping any special part and stinui- 

 lated only those which were immediately beneath those that had been 

 lifted. In carrying on the experiment in this way it was possible 

 to locate quite accurately the extent of this kind of hair sensibility 

 and the error of determining the line of division between sensitive 

 and non-sensitive parts was not more than a few millimeters. 



The results of this careful examination were quite unusual and 

 wholly unexpected. T found the hairs to be sensitive to stimulation 

 of cotton wool or of the liffht camel's hair brush in all the areas 



