272 BEVIEWS. 



what is the extent of the lesion. This is the means that I always employ in my ex- 

 periments, and it is also the means employed by the Committee appointed by the 

 Societe de Biologic, for the investigation of my researches on the spinal cord." 



"We think then, that notwithstanding the great and admitted diffi- 

 culties which surround experimentation on the spinal cord, much 

 weight must be given to testimony derived from results tested by so 

 rigid a process. In his second lecture, Dr. Brown- Sequard details 

 the experiments by which he hopes to prove that the transmission 

 of sensitive impressions in the spinal cord, takes place chiefly in its 

 central part, i. e. in the grey matter; and in the following discourse, he 

 enters upon those which show that the conductors of sensitive impres- 

 sions from the various parts of the trunk and limbs, make their decus- 

 sation in the spinal cord, and not in the encephalon, as had been 

 generally supposed. He commences by proving that the theory of 

 Longet, with regard to the posterior columns of the cord being the 

 conductors of sensitive impressions, is no longer tenable ; he carries on 

 the work of destruction commenced by Sir Charles Bell himself, 

 vigorously urged on by the serious objections brought up against this 

 hypothesis by Dr. B. B. Todd, supported more recently by the beau- 

 tiful anatomical researches of Stilling and Lockhart Clarke, and now 

 completed by his own experiment, showing that a transverse section 

 of the posterior columns, far from being followed by any loss of feeling 

 is accompanied by the very reverse effect. So far as the posterior 

 columns are concerned, this single experiment annihilates the fasci- 

 nating theory of Longet, which won its way so speedily into full 

 notoriety, and was so charmingly seductive, because "it was so 

 orderly a plan and made people remember." But it had no facts to 

 rest upon. 



If, says our author, the transmission of sensitive impressions does 

 not take place along the posterior columns, it remains to be found 

 what is the channel of their transmission. Is it the grey matter, or 

 some part of the lateral or anterior columns, or all, or several, of these 

 constituents of the spinal cord ? "When the anterior columns alone 

 are divided there is no marked alteration of sensibility. Trans- 

 verse section of the two lateral columns, in the dorsal region, does not 

 diminish, but increases, sensibility in the posterior limbs, while sensi- 

 bility is lost in these parts when the entire spinal cord, with the ex- 

 ception of one lateral column, is divided transversely ; hence, it seems 

 that sensitive impressions are not transmitted through these channels. 

 It is quite different with regard to the grey matter. 



A transverse section of the posterior half of the spinal marrow is 

 attended with diminished sensibility in the posterior extremities, but as 

 we already know that this loss of sensibility is not attributable to the 

 division of the posterior, and the portions of the lateral, columns thus 

 unavoidably divided, it 'seems necessarily to be due to the division of 

 the grey matter. Again, transverse section of the anterior half of 

 the spinal cord is also attended with diminished sensibility ; but, since 



