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II. " Summary of a paper (to be presented) entitled Experi- 

 mental Researches on the Spinal Cord as a leader for 

 Sensibility and Voluntary Movements." By E. BROWN- 

 SEQUARD, M.D. Communicated by JAMES PAGET, Esq., 

 F.R.S. Received June 25, 1857. 



The new field opened by the genius of Sir Charles Bell is enlarging 

 every day, and interesting advances in Physiology and Pathology are 

 constantly being made which are due to the admirable discoveries 

 of this eminent biologist. The following results of my experiments 

 are new developments of these discoveries. 



I. It has been well proved by the researches, of which I have 

 already published the results, that the nerve- fibres employed to 

 convey sensitive impressions, may be deprived of sensibility, so that 

 the property of being sensitive and that of conveying sensitive im- 

 pressions are distinct one from the other. A similar distinction 

 must be made as regards the voluntary motor nerve-fibres. I have 

 found them inexcitable by some of our means of excitation in places 

 where there are a great many of them conveying the orders of the 

 will to muscles. When we introduce a needle gently through the 

 medulla oblongata from behind forwards, traversing successively one 

 of the restiform bodies, the descending root of the trigeminal nerve, 

 some gray matter and the anterior pyramid, not only the animal does 

 not give signs of pain, but there is usually no movement produced in 

 any part of the body. The precautions which must be taken to 

 obtain this result are described in the paper ; I will merely say here 

 that if the needle is introduced obliquely instead of perpendicularly, 

 a spasm of the muscles of the neck occurs, and sometimes the animal 

 rotates. 



This experiment shows that the irritation of the anterior pyramids 

 with a needle, does not excite more movement than that of the cere- 

 bral lobes, although these pyramids are certainly channels for the 

 transmission of orders of the will to muscles. It results from this 

 fact, that the conclusion, drawn by some physiologists, from the inex- 

 citability of the cerebral lobes, that the voluntary motor nerve-fibres 

 do not go into them, is not well-grounded. 



