Meyer, Data of Modern Neurology. 2^1^ 



should think that a cut anywhere in this path and Hmited to 

 this path should cause anaesthesia to any irritation. This we 

 know to be established for two portions of the path only. First, 

 the afferent segmental neurone as far as its entrance into the 

 spinal cord ; and second, less convincingly, in the fillet from its 

 nucleus to the thalamus ; higher up only when a large part of the 

 thalamic radiation and the cortex belonging to it is involved. In 

 the 'segmental region,' the spinal cord, etc., the matter is by no 

 means clear. Brown-Sequard, in a criticism of the experiments of 

 Mott (which spoke in favor of the anatomical path) gave up the 

 well-known plan of the immediate decussation which tries to do 

 justice to the symptom-complex of the Brown-Sequard paraly- 

 sis. He states that not only hemi-section of the cord but also 

 section oi ihQ posterior roots in the upper thoracic segments may 

 produce a hyperaesthesia of the hind-leg of the same side 

 and an anaethesia of the opposite side. Further, if by a hemi- 

 section of the cervical cord a contralateral anaesthesia is pro- 

 voked, it can be reversed into hyperaesthesia by a second hemi- 

 section in the thoracic cord, whereas the hyperaesthesia exist- 

 ing on the same side passes over into anaesthesia. The Brown- 

 Sequard symptom-complex undoubtedly exists, but the anatom- 

 ical explanations are hardly adequate. If we add further pecu- 

 liar facts, such as the paralysis of a limb when all its ' sensory ' 

 roots are cut while the motor are intact (Sherrington), and all 

 the scattered data on hyperaesthesia, on muscular, tactile and 

 temperature senses, we should begin to feel that certain activi- 

 ties of the segments escape our attention and make no psychi- 

 cal impression except by the filial results. The result of a sum 

 represejits items, but \s 7tot a pictiwe oi the summation, just as 

 little as the figure 7 should be a composition of the figures 3 

 and 4 as an evidence for 3 plus 4 being 7, or just as little as we 

 are conscious of which nerves and muscles are going to contract 

 and relax when we catch a fly. We are radically wrong if we 

 try to translate psychic phenomena uncritically into anatomical 

 structures and believe that the plan of analysis and subdivision 

 of psychic processes can be read piece by piece in the parts of 

 the anatomical substratum. To return to the simile: who 



