Franz, Sctisations follrnvnig Nerve Division. 121 



cause a sensation in the area A is normal, while the threshold values 

 in B and C are greater than normal. This gradual change from 

 no sensation to a normal sensibility threshold is striking. The results 

 show that there is no sharp line separating the areas of protopathic 

 and epicritic sensibilities, and it appears that the changes in the 

 nervous system are more widespread than has hitherto been sup- 

 posed. On the hand and arm the line separating the area in which 

 the epicritic sensibility was lost from that in which it was retained, 

 is sharply defined by cotton wool or by carael's hair pressure, but 

 in view of the more quantitative experiments with the touch in- 

 strument of Bloch this line must be considered a very rough 

 approximation, for the experiments show that the sensibility dis- 

 turbance extends much beyond this line. For the distance of two 

 centimeters beyond the line of epicritic sensibility loss, normal 

 sensibility threshold as measured by the esthesiometer was not found. 

 These results may be explained in a number of different ways. 

 At first sight they appear to confirm the hypothesis which has been 

 advanced to explain all the results of Head and Sherren, namely, 

 that we are dealing with differences in threshold value when we speak 

 of epicritic and protopathic sensibility. The results which have 

 been obtained on the sensibility to temperature and the result on 

 the sensibility of the hairs are not in accord with such a hypothesis. 

 It appears to me more likely that the gradual approach from the area 

 of deep sensibility loss to the perfectly normal area, especially the 

 gradual lowering of the threshold along the area in which the epi- 

 critic sensibility is present, indicates that there is an overlapping of 

 the nerves as the anatomists used to teach, and which Flead assumes 

 is disproven by his discovery of the various forms of deep, protopathic 

 and epicritic sensibilities. According to the accounts and conclusions 

 published by Head and his co-workers, it would appear that there is 

 no overlapping of these nerves, but a critical analysis of the cases 

 published by Flead and Sherren shows that they always found such 

 an overla]')])ing. For example, if we consider carefully the diagrams 

 published by Head of the distribution of the median, ulnar and 

 superior radial nerves of the hand, we find on the palm, the ulnar 

 nerve is supposed to innervate that part of the palm which is on 



