120 'Hemisection of the Spinal Cord in Monkeys. [June 18, 



June 18, 1891. 

 Sir WILLIAM THOMSON, D.C.L., LLD., President, in the Chair. 



The Presents received were laid on the table, and thanks ordered 

 for them. 



Professor Daniel John Cunningham, Professor Percy Faraday 

 Frankland, and Mr. William Napier Shaw were admitted into the 

 Society. 



The following Papers wer.e read.: 



I. "Results of Hemisection of the Spinal Cord in Monkeys." 

 By FREDERICK W. MOTT, M.D., B.S., M.R.C.P. Communi- 

 cated by Professor SCHAFER, F.R.S. Received June 1, 



1891. 



(Abstract.) 



While engaged in studying experimentally the connexions of the 

 cells of Clarke's column with the ascending tracts of the spinal cord 

 in the monkey, I was surprised to find that after hemisection in the 

 lower dorsal region the sensory disturbances produced in no way 

 corresponded with those already obtained by eminent observers. 



I was, therefore, led to continue my experiments, and, by the kind 

 permission of Professor Schafer, I carried them out in the Physio- 

 logical Laboratory of University College. My thanks are also due to 

 him for much valuable advice and assistance. 



The subject is one of great importance from a scientific, as well as 

 from a clinical ,,point of view. Some years ago, a case occurred in my 

 practice which tended to shake my faith in the absolute truth of the 

 doctrine of complete and immediate decussation of sensory impulses 

 in the spinal cord, as taught by Brown -Sequard. 



The experiments which I have performed exhibit the following 

 principal points of interest : 



1. Return of associated movements after complete destruction of 

 the crossed pyramidal tract below the lesion. 



2. That all sensory impulses do not decussate in the cord, in fact, 

 they appear to show that certain sensory impulses, e.g., touch, the 

 muscular sense and localisation in space, pass chiefly up the same side, 

 painful impressions up both sides. A peculiar condition known as 

 "allochiria " occurs after hemisection. 



