556 Mr. Graham Brown. Alleged Specific Instance of [Dec. 9, 



His first papers date from the year 1850 (1, 2, 3, 4, 5), and he continued to 

 investigate the phenomenon for more than 40 years, publishing his results in 

 a series of papers and short notes.* 



He found that the condition might be produced by means of many 

 different lesions. Of these, it is necessary here to refer only to section 

 of the great sciatic nerve (9, 11, 12, 13) ; to amputation of the leg, that is, 

 section of the various nerves of the leg (18); and to section of the lumbar 

 posterior spinal roots, which supply the great sciatic nerve (12). 



A detailed account of these experiments, in so far as they concern the 

 phenomenon, and not its transmission, has been given by the author in 

 another place (45). 



The condition may be described as it occurs after removal of a part of 

 one great sciatic nerve. At a variable time after the production of the 

 lesion, a rapid scratching movement of the hind limb of that side is evoked 

 on gently pressing the skin of the face upon the same side as the lesion. 

 The pressure must be applied within a definite area — the " epileptogenous 

 zone " of Brown-S^quard — and is ineffective if applied to the corresponding 

 area of skin upon the other side of the body. This reaction constitutes the 

 " incomplete attack." The scratching is accompanied by a twisting of the 

 neck and back. 



As time elapses, after the appearance of this condition, the phenomenon 

 enters upon a second phase — that of the " complete attack." Here the 

 twisting of the back and neck becomes more pronounced, and the animal 

 loses its balance. At a point in the phenomenon the sense of the bending 

 in back and neck reverses, and the loss of balance is possibly a result of tbis. 

 With the change in the direction of the curvatures, the scratching movements 

 usually cease in the hind limb of the side of the lesion, and then appear in 

 the opposite hind limb. The scratching shortly again changes sides, and so 

 the movements alternate from side to side of the body. This " attack " may 

 continue for a minute or more after the mechanical stimulation of the skin 

 of the face or neck has ceased (fig. 1). 



Brown- Sequard has been confirmed by many observers in his general 

 description of the appearances of this condition. Two points may be 

 especially noted. The first of these is that the phenomenon is a clearly 



* In the absence of a satisfactory bibliography the search for Brown-Sequard's 

 original communications necessitates much labour. I have therefore given a list of his 

 most important publications at the end of this paper. Eeferences to these papers in the 

 text are indicated by numbers in brackets. This list supplements another given by the 

 author (45), in which the papers deal with the physiological aspect of the condition. 

 Neither list is complete, for I have probably not read all the original papers, and many 

 of those which I have read it was unnecessary to quote. 



