Franz, Sensations Fol/muing Nerve Division. 233 



explauation would also account for the less widely felt sensations 

 from the medium degrees of temperature when the individual square 

 centimeters were separately stimulated. Such an explanation would 

 not account, it seems to me, for the results which were obtained when 

 an extended line was stimulated rather than a small area. It appears 

 more probable that, as Head contends, for temperature sensations 

 we have two sets of nen^es, one of which responds to the extremes 

 of temperatures and the other to the medium temperatures. These 

 two sets of nerves correspond to the fonns of sensibility that are 

 called respectively protopathic and epicritic, but in a different way 

 than that described by Head and his co^-workers. The results from 

 my subject show that, although hot and cold stimuli produce sensa- 

 tions in areas endowed with the protopathic fomi of sensibility, 

 the sensations correspond to those produced in normal areas by 

 stimulation with medium temperatures. This at first sight looks 

 as if we were dealing solely with differences in threshold values, 

 but this hypothesis does not account for another apparently anomalous 

 condition which was found by Head and Sherren, viz., the loss 

 of the ability to sense the extremes of temperatures wdth the reten- 

 tion of the ability to sense medium temperatures. 



It seems to me that the temperature results, taken in connection 

 with those which have been described in my articles on the 'Pressure- 

 like' and 'Hair Sensibilities,' show there is an overlapping of the 

 nerves, or rather there is an overlapping of nerve supply, and that 

 the sensation differences which were found in this case are to be 

 explained as due to the presence or absence of certain nerve endings 

 or of nerve fibers. It is j)ossible that the sensations of coolness and 

 warmth are protopathic, w'hile those of coldness and hotness are 

 epicritic. This, it will be observed, is contrary to Head's belief. 

 Received for piiblieation December 7, 1908. 



NoTE.^Since the articles on sensations following nerve division were written 

 I received the number of Brain in which Rivers and Head give the results of 

 careful examinations made on Head's arm in which the radial nerve was 

 divided near the elbow (W. H. R. Rivers and Henry Head. A Human 

 Experiment in Nerve Division. Brain, 1908, vol. 31, Part 123, pp. 323-450). 

 Some of tlie new observations reported by Rivers and Head indicate a con- 

 dition on Head's arm similar to that found by me on H., but some of these 



