BROWN- SEQUARD ON THE CENTRAL NERVOUS SYSTEM. 281 



view wants further evidence for its complete substantiation, we wish 

 to state what exactly are his notions on this subject. It seems to him 

 that the conductors of the various sensitive impressions pass along 

 distinct fibres, which decussate in the spinal cord : that none of them 

 go up to the brain along the posterior columns. It remains, in his 

 opinion, to be known where the decussation takes place for the nerve 

 fibres conveying different sensitive impressions, but he conceives that 

 for all sorts of sensitive conductors save one, there is evidence that their 

 place of decussation is in the immediate neighbourhood of the entrance 

 of the posterior roots into the spinal cord ; the conductors of the kind 

 of sensitive impressions which originate in muscles when they contract, 

 — impressions which, on being felt, guide our movements, — perhaps 

 form an exception and decussate very high in the spinal cord : in sup- 

 port of which, Dr. Brown-Sequard cites the fact that in most of the 

 cases of alteration of a lateral half of the spinal cord which he has re- 

 ported, the voluntary movements are said to have been unimpeded on 

 the opposite side of the body, which would not have been the case if 

 the " guiding sensation" had not been felt. In one of these cases, how- 

 ever (case 37), the patient had lost that peculiar muscular sensibility 

 which guides voluntary movement, as she could not hold her child in 

 her arm when she did not look at that arm. But as the precise seat 

 of alteration in this case was not known, no positive conclusion can 

 be drawn from it : it would only seem to show that the fibres of mus- 

 cular sense do not decussate, along with those for muscular motion, in 

 the decussation of the anterior pyramids. Before passing on to the 

 consideration of the very important discoveries of modern physio- 

 logists, concerning vaso-motor nerve fibres, we may observe that even 

 though it be assumed by some that there are distinct conductors for 

 various sensitive impressions, yet it appears certain that such con- 

 ductors do not run in distinct bundles, along definite tracts of the 

 spinal cord, any more than do the nerve fibres seem to run in groups 

 or distinct bundles, from the surface supplied by them, to the brain. 

 Were it so, and admitting that sensitive impressions are mainly pro- 

 pagated along the grey matter, it would follow that certain injuries 

 done to the grey matter, but not dividing it completely, would be 

 followed by loss of some particular variety of sensation, or, in the 

 other instance, by anaesthesia in particular patches of the surface 

 from which the divided bundles of nerve fibres would have come. 

 But this is not what occurs ; after lesion of the spinal cord, engaging 

 more or less of the grey matter, sensibility is not completely destroyed 

 in certain places, remaining perfect in -other parts: but sensibility is 

 diminished and apparently, equally diminished, in all parts posterior 

 to the lesion, and this diminution of sensibility continues to become 

 more marked, the more the grey matter is divided, until, when the 

 anterior columns alone remain, anaesthesia is established. Thus, while 

 one is certainly induced to believe that the grey matter of the cord con- 

 ducts sensitive impressions as a whole, and not, as a nerve, by separate 

 conductors coming from particular points — it is evident that the 



