70 



Scientific Proceedings (56). 



qualities of cutaneous contact, cutaneous pressure, and deep 

 pressure, all of which can be distinguished by practice; between 

 warmth, heat, and burning heat (the last two are complex); and 

 to some extent between the different modes of cutaneous pain. 

 Besides this special training, the subject has had the advantage of 

 general introspective practice, obtained during several years of 

 psychological investigation. 



2. The final introspective practice series were so arranged as 

 to supply objective norms for that area of the skin which was 

 afterwards affected. 



3. The selection of the nerve for section was such that the 

 region affected was sufficiently small to permit of a more careful 

 exploration than would have been possible if it had been necessary 

 to cover a large area. 



4. Except for purposes of comparison with other researches, 

 areal stimuli were discarded as not sufficiently adapted to the 

 investigation of the skin, in which sensibility is distributed in a 

 punctiform manner. Emphasis was laid upon the isolation of the 

 separate sensory spots, and an effort was made to determine, not 

 only the strength of stimulus which would just arouse sensation 

 in each one of these spots, but also the intensity of sensation 

 aroused in each one by a constant strength of stimulus. For 

 pressure, hairs were employed; and for pain, two needle algesi- 

 meters. Warmth and cold were studied by means of a hollow 

 brass cylinder through which water of different temperatures was 

 passed. The cylinder was drawn over the skin by a kinesimeter, 1 

 which controlled the rate of exploration and the pressure of the 

 stimulus ; a record of the position and of the intensity -value of the 

 spots was taken simultaneously on a kymograph drum. 



5. Orientation on the surface of the arm was obtained in most 

 of the work by means of coordinate lines, impressed in a given 

 relation to a set of tattoo marks by a rubber stamp. More 

 accurate localization of the points was secured by placing the arm 

 in a permanent plaster cast, to which was rigidly attached a 

 vernier stage, carrying an indicator, that moved just over the 

 surface of the skin. By reference to the indicator and the vernier 

 scales, points could be identified to within less than one half 

 of a millimeter. 



1 Am. Jour. Psychol., 6, 1894, 424; 7, 1895, 150. 



