120 'Journal of Comparative ~N eurology and Psychology. 



a threshold average of 29, while a similar, nuiiiber of corresponding 

 points of the right thumb gave an average of S.T. On the ball and 

 on the back of the third joint of the thumb eleven experiments on 

 the left hand averaged 42,1, and on the right, 20.5. 



On the upper part of the forearm, a section including the area 

 in which different forms of sensibility were altered, was carefully 

 crossmarked in centimeter square divisions. This section of the area 

 was carefully shaved so that these experiments could be carried out. 

 Each of the thirty-five squares was then carefully tested five times. 

 The averages were calculated and the results of these examinations 

 are given in Table II. 



TABLE II. 

 Touch Thresholds on Volar Side of Forearm. 



Bloch Instrument B. 



*Ap])roxiinate. 



The results for the five horizontal centimeter squares are grouped 

 in this table. Below G the arm did not respond to temperature 

 stimuli, nor to the stimulation of the hairs. Areas A, B and C 

 reacted to all forms of temperature stimuli with sensations of hot- 

 ness, warmth, coolness and cold, while area I) responded to only 

 some of these. These areas also gave results to brushing and pulling 

 the hairs, while plucking the hairs in areas E, F and G gave no 

 sensations. A full account of the results on the hair and temperature 

 sensations in these areas will be found in a subsequent article. It 

 is sufficient for the present to know that areas E, E and G were 

 clearly devoid of epicritic sensibility, M'hen areas A, B and C were, 

 in accordance with Head's methods of examination, clearly normal. 



In G and F the stimulus was perceived only once, although tlu; 

 instrument was pressed to its highest point. Twice in area E stimuli 

 were perceived, seven times in area D, and always in areas C, B and 

 A, w^hen the pressure of the tension of the instrument became suf- 

 ficient. A comparison of these results with the results of a similar 

 examination of the right arm show that the stimulus necessary to 



